Jurgen Klopp's side hadn't conceded in the top flight since Dec. 4 but Raul Jimenez cancelled out Jordan Henderson's first-half header shortly into the second half. Both sides had chances to win it before Firmino struck a typically late winner to extend Liverpool's winning streak to 14 games and restore their lead atop the Premier League to 16 points.
Takumi Minamino made his Liverpool debut after officially joining from RB Salzburg at the start of the month for a fee believed to be £7.25 million. Though his impact was minimal, the 25-year-old was thrown into one of the Premier League's more hostile atmospheres at Molineux.
Though their Premier League clean sheet run ended, Virgil van Dijk delivered an excellent performance to undoubtedly deny Wolves any points.
The biggest negative from Thursday evening is without question how Liverpool played following Sadio Mane's injury. The visitors lacked energy, speed and forward-thinking once the 27-year-old was forced off after half an hour.
Manager rating out of 10
7 -- Klopp made few changes before the match but was forced to deal with the huge loss of Mane with a little over a half-hour played, and trusted Minamino to make his debut in a big spot. Clearly animated on the touchline and maybe didn't get the best out of his players, but they still dug in to grind out a win -- a true sign of a championship team.
Player ratings (1-10; 10 = best, players introduced after 70 minutes get no rating)
GK Alisson, 8 -- Little to report in the first half, though he misjudged what should've been a simple catch to almost grant Wolves a cheap sight on goal. Could do little about Jimenez's equaliser before a number of world-class saves helped Klopp's side preserve their unbeaten top-flight record.
DF Trent Alexander-Arnold, 7 -- Wasn't without his errors initially but delivered an excellent cross from a corner to tee up Henderson for Liverpool's opener. Great deliveries from set pieces which always caused Wolves a threat.
DF Joe Gomez, 7 -- Had his moments of nervousness but equally showed great levels of composure to thwart a confident Wolves in their search for an unlikely winner. Perhaps played best when under extreme pressure.
DF Virgil Van Dijk, 8 -- While there was occasional defensive nervousness from those around him, Van Dijk marshalled the back four well and made a number of brilliant blocks, too. His passing was exemplary.
DF Andy Robertson, 5 -- Slipped to opened space up for Wolves in the seconds ahead of their equaliser, and he struggled all evening to deal with the physicality and pace of Traore. Picked up a yellow card as well on a night that was far from his best.
MF Alex Oxlade-Chamberlain, 5 -- Was never able to get a foothold in the game -- perhaps epitomised when Mohamed Salah neglected to make a pass in his direction despite being well positioned to shoot. No great surprise when he was subbed with 20 minutes remaining.
MF Jordan Henderson, 9 -- Brilliant spatial awareness to avoid Joao Moutinho's presence before and during the set piece that granted Liverpool their opener via his shoulder. Grabbed a late assist too when he picked out Firmino to strike the visitors' late winner.
MF Georginio Wijnaldum, 6 -- Much like Oxlade-Chamberlain, the Dutchman had a quiet game in midfield and never really got involved in the creative side of the visitor's play. Wolves certainly exposed gaps in midfield, and he will definitely enjoy better games.
FW Mohamed Salah, 7 -- Got into great pockets of space in both halves but was generally a little selfish when pulling the trigger at times where better options were available. Further chances in the second half weren't taken either, though he was involved in what proved to be the winning goal.
FW Roberto Firmino, 7 -- A handful of midfield and defensive errors did little to help the Reds' forward movement in the first half. Was quiet for much of the second half but grabbed a smash-and-grab winner in the final 10 minutes when he fired into the top corner after Henderson's slick assist.
FW Sadio Mane, 7 -- Possessed his usual creative flair and was unlucky not to bag an assist in the half-hour he played before a suspected hamstring injury forced him off. Liverpool is hoping it isn't serious.
FW Takumi Minamino, 6 -- Big boots to fill when coming on for Mane but slotted into the team well in a tough environment. Will benefit from the experience.
MF Fabinho, 6 -- A key change by Klopp that perhaps turned the game on its head with Oxlade-Chamberlain struggling to make an impact.
FW Divock Origi, N/R -- Replaced Salah in the closing stages and didn't have much to do.