The teams met four times in the old European Cup -- twice in 1958 and two more times in 1969 -- before failing to cross paths again in European competition for another 36 years. That prolonged estrangement finally came to an end in February 2005 when United and Milan met in the Champions League for the very first time, 13 years after the competition was rebranded.
Flying high at the top of the Serie A table at the time, a star-studded Milan side coached by Carlo Ancelotti travelled to Old Trafford to be pitted against Sir Alex Ferguson's United in the round of 16. The Rossoneri won both legs by a single goal to nil, the first of which saw a first European home defeat inflicted on United in over four years. United thought they had won to nil again this week, through Amad Diallo's goal, only for Simon Kjaer to level two minutes into stoppage time.
Both starting XIs when the teams faced off in 2005 were positively brimming with A-list names, many of whom either already boasted or soon went on to achieve Champions League greatness. Here's a rundown of the 22 players who stared the first leg, and a look at where they are now.
13. Roy Carroll, GK
Having failed to inspire much confidence among United fans with a series of costly blunders, Carroll endured a night to forget at Old Trafford as another untimely error handed -- or rather chested -- the decisive goal to Milan. Two months later, the Northern Ireland international was released by United and signed for West Ham on a free transfer. At the age of 43, Carroll is one of only two players on the pitch during the United-Milan game to still be active in a senior professional capacity to this day. Indeed, he signed for Dungannon Swifts as player-goalkeeping coach in January 2020 and has made seven appearances in the Northern Irish top flight.
2. Gary Neville, RB
Having celebrated his 30th birthday just five days prior to the game, Neville lasted 80 minutes before being taken off and replaced by Mikael Silvestre. The dependable right-back went on to make 599 appearances for United, winning eight league titles, three FA Cups, two League Cups and two Champions Leagues before retiring from the game in 2011. Now 46, Neville is a staple on the Premier League punditry scene having found out the hard way that he wasn't really suited to management following a disastrous stint in charge of Valencia.
6. Wes Brown, CB
Brown rose through the academy and youth ranks at United and became a dependable presence at the heart of their senior defence for many years. He played a part in five Premier League titles (the first being United's famous treble in 1998-99) and two Champions League triumphs for United before departing to spend the final stretch of his career with Sunderland (2011-16), Blackburn Rovers (2016-17) and Kerala Blasters (2017-18). Brown, 41, still serves as an ambassador for United, regularly taking part in charity activities, community programmes and "Legends" exhibition matches.
5. Rio Ferdinand, CB
Ferdinand played 455 times for United, the club that made him the most expensive British signing when they plucked him from Leeds for £30m in 2002. The cultured centre-back was instrumental in six title wins in the space of a decade between 2003 and 2013, as well as United's run to glory in the 2007-08 Champions League. Ferdinand left Old Trafford at the end of the 2013-14 season to see out the final year of his professional career at QPR, before retiring in the summer of 2015. Since then he has found regular work as a television pundit and even flirted with the idea of becoming a boxer -- only to see his application for a pro licence rejected by the British Boxing Board of Control in 2018.
4. Gabriel Heinze, LB
After representing Real Madrid, Marseille and Roma in the years following his United departure, Heinze returned home to Argentina to spend the final two seasons of his career with Newell's Old Boys. He then transitioned into management after retiring and was able to make a decent fist of it with fair spells at Godoy Cruz, Velez Sarsfield and Argentinos Juniors, with whom he won the Primera B title in 2016-17. In December, Heinze was named manager of MLS club Atlanta United on a two-year contract.
25. Quinton Fortune, RW
Having concluded his professional career with a brief and largely forgettable season at Doncaster Rovers in 2009-10, Fortune returned to United to train with the reserves while he studied for his coaching badges. A succession of coaching jobs followed, and the South African was appointed as first-team assistant at Championship side Reading in September 2020, along with former Red Devils teammate John O'Shea.
11. Ryan Giggs, LW
An undisputed modern great at United, Giggs made his league debut for the club in March 1991 and played on until May 2014, when he finally retired at the grand old age of 40 having made over 1,000 competitive appearances and won just about all there was to win. Giggs became United's interim player-manager when he filled the breach left by David Moyes' sacking for the final few weeks of the 2013-14 season, before taking a role as Louis van Gaal's assistant when the Dutchman was chosen as Moyes' permanent successor that summer. Now 47, he has been head coach of Wales since 2018, successfully securing Euro 2020 qualification along the way.
16. Roy Keane, CM
Keane was club captain at United during one of their most successful periods, winning seven Premier League titles, four FA Cups and the Champions League. After the Milan game, the infamously volatile midfielder saw out the remainder of the 2004-05 campaign at Old Trafford only to leave a few months into the next, joining Celtic after falling foul of United's disciplinary directives one too many times. He retired on medical advice aged 34 due to a persistent hip injury in the summer of 2006. Keane turned to management, and got Sunderland into the Premier League against all the odds. But a subsequent spell at Ipswich wasn't so successful. After spells on the coaching staff with Republic of Ireland, Aston Villa and Nottingham Forest he now regularly works as a television pundit, lending some of that trademark acerbic analysis.
18. Paul Scholes, CM
Another United legend to have won a vast array of trophies, making 710 appearances having first come through the youth ranks as a member of the fabled "Class of '92." Having made his debut in 1993, Scholes even played on long enough to retire twice; first bowing out at the end of the 2010-11 season, before staging a dramatic return to the United first team which lasted until his second (and final) retirement in May 2013, aged 38. He's since dabbled in management with hometown club Oldham Athletic, though his tenure only lasted 31 days. Scholes also filled in as caretaker manager of Salford City, the League Two club he co-owns with fellow Class of '92 alumni Ryan Giggs, David Beckham, Nicky Butt and Gary Neville, as well as Phil Neville. He now works as a pundit.
8. Wayne Rooney, CF
Aged 19 at the time, Rooney was deployed as a lone striker against Milan but unsurprisingly struggled to make many in-roads against one of the most well-drilled defensive lines in the world. He remained at United for a further 13 years, becoming the club's all-time record goal scorer before winding down his playing days with boyhood club Everton, DC United and Derby County. Upon retiring in January this year, 35-year-old Rooney took over the reigns as head coach at Derby, thus taking his first tentative steps into the world of management.
7. Cristiano Ronaldo, FW
Other than goalkeeper Carroll, Ronaldo is the only other member of United's starting XI against Milan in 2005 to still be active. Indeed, the 36-year-old is still playing at the very top level with Juventus, having spent the intervening years scoring truly bewildering amounts of goals and winning league titles, domestic cups, Champions Leagues, the European Championship and Ballon d'Ors galore with Real Madrid. On the night, a spindly 20-year-old Ronaldo put in a rather subdued performance and was eventually replaced by Ruud van Nistelrooy on 62 minutes, as the Dutch striker made his comeback from a two-month injury layoff.
1. Dida, GK
Dida spent a highly successful decade with Milan, winning the Champions League twice before returning home to his native Brazil in 2010 to see out his playing days with Portuguesa, Gremio and Internacional. He has since become a goalkeeping coach, starting with an intern role at Internacional while he progressed through his qualifications. The 47-year-old returned to Milan in 2018 after landing a job coaching the Rossoneri youth teams, though a promotion ahead of the 2020-21 season saw him take over as goalkeeping coach to the senior side.
2. Cafu, RB
Despite retiring in 2008 and turning 50 last year, Cafu has retained his incredible fitness and stamina levels to this day and thus can still be regularly found terrorising opponents many years his junior while tearing up and down the right flank during Milan Legends games. Cafu is now an ambassador for Qatar's Supreme Committee for Delivery and Legacy, the body responsible for organising the 2022 World Cup,
3. Paolo Maldini, CB
Quite simply one of the greatest defenders of his or any era, a 41-year-old Maldini made his 901st and last appearance for Milan -- the club he first joined as a 10-year-old -- in 2009 before bowing out gracefully, without much in the way of fanfare. The Rossoneri then retired his iconic No. 3 jersey as a gesture of appreciation for the retiring veteran's 25 years of esteemed service. Several years later, Maldini attempted to embark upon a semi-professional tennis career, but alas it didn't go particularly well -- getting thrashed inside 42 minutes on his tournament debut in 2018. Both of Maldini's sons, Daniel and Christian, played for Milan's youth teams, with the former having already made his senior debut -- thus becoming the third generation of the Maldini family to play for the club.
13. Alessandro Nestam CB
It's perhaps unfair that Milan were able to field two of the very finest defenders in the Italian footballing pantheon at once, as Nesta sat alongside Maldini to comfortably keep United at arm's length. Nesta's coaching career began in 2017 when he was named as the boss of NASL franchise Miami FC, though the Italian resigned after just one season. He returned home to take charge of Serie B side Perugia in 2018 before moving on to Frosinone the following year, guiding the side into the promotion playoffs in his first campaign.
4. Kakha Kaladze, LB
The Georgian defender played 284 times for Milan during a distinguished career, though has since left the football world behind after making the move into politics. Now 43, Kaladze is the current mayor of capital city Tblisi having previously served as the minister of energy and both the second and first deputy Prime Minister of Georgia since 2012.
8. Gennaro Gattuso, CM
A fiery and combative midfielder, Gattuso retired in 2013 after leaving Milan to spend a single season in Switzerland with FC Sion as a player-coach. The 43-year-old is now head coach of Napoli, having already returned to manage his beloved Milan for two years between 2017 and 2019.
21. Andrea Pirlo, CM
One of a select group of players to represent AC Milan, Inter Milan and Juventus, Pirlo bowed out in 2017 after spending the final two years of his playing career in MLS with New York City FC, where he struggled with injury. "The Metronome" has since moved into management, landing his first coaching role with Juve's under-23 side in July 2020. This lasted all of nine days as Pirlo found himself quickly promoted to the position of head coach of the men's senior side following the dismissal of Maurizio Sarri in August.
20. Clarence Seedorf, CM
One of the most decorated footballers of all time, Seedorf made 482 appearances for Milan where he won two Serie A titles and two Champions Leagues, as well as enjoying successful stints with Ajax, Inter Milan and Real Madrid. The Dutchman finished playing with a two-season jaunt at Brazilian side Botafogo before becoming a coach thereafter, terminating his contract early to take the vacant Milan job in 2014. Seedorf has since been appointed as head coach of Chinese side Shenzhen in 2016 but he was replaced by Sven Goran Eriksson after a few months. He then headed to Spain with Deportivo La Coruna in 2018, but they were relegated after just two wins in 16 matches. His last post to date was as manager of the Cameroon national side in 2019 but he was sacked after they failed to get beyond the round of 16 at the Africa Cup of Nations that year.
22. Kaka, AM
One of two playmakers deployed behind a lone striker against United, Kaka made 307 appearances for Milan over two spells, scoring well over 100 goals. The Ballon d'Or winner retired from football at the age of 35 after his contract with Orlando City expired in 2017 but he still crops up in the odd five-a-side game in Hackney.
10. Rui Costa, AM
With 10 years separating the pair, 32-year-old Rui Costa fulfilled the second of Milan's attacking midfield playmaker roles alongside Kaka. The Portuguese great spent the majority of his club career in Italy with Fiorentina and the Rossoneri, with whom he won a title and a Champions League in successive seasons (2002-03 and 2003-04). Costa has since become a club director, being handed the position at Benfica the very day after his final professional game in 2008.
11. Hernan Crespo, ST
On loan from Chelsea at the time, Crespo only started against United as Andriy Shevchenko (who was reigning European Footballer of the Year at the time) was still recovering from a broken cheekbone. The Argentine striker went on to score the only goal of the game on 78 minutes after benefitting from Carroll's handling gaffe to tap the ball home. Crespo scored 17 goals in 40 appearances before joining rivals Inter in 2006 (again, initially on loan) and subsequently winning the 2008-09 Serie A title on the other side of the city. Having retired in 2012, the 45-year-old began his coaching career with Parma under-19s and is currently head coach of Sao Paolo, having been appointed by the Brazilian club in February 2021.