Rakitic struck in the 71st minute of a tense game that was dominated by Barca but lacking in chances. The Croatian fired past Unai Simon after being teed up by Lionel Messi, who twice came close to doubling the home side's lead late on. Ansu Fati also hit the post from point-blank range right before the full-time whistle.
Barca defender Gerard Pique says it will be "very difficult" to win the league after ceding top spot to Madrid at the weekend. Barca will have to win each of their reaming seven games and hope Zinedine Zidane's side drop points somewhere along the way. That means they will have to win however possible and when they're not at their best -- which is what they just about managed against Athletic, although they improved in the second half.
The wins are more likely to come if they can maintain their impressive form at the back. This was a fifth clean sheet in a row for goalkeeper Marc-Andre ter Stegen.
There were also positive contributions off the bench from youngsters Riqui Puig and Fati. Both made a good case for more minutes moving forward.
Sergio Busquets has been one of Barca's better performers since the restart so to lose him for Saturday's trip to Celta Vigo -- who are fresh from hammering Alaves 6-0 at the weekend -- is far from ideal. He will be suspended after picking up his fifth booking of the season here. Frenkie de Jong, who has a calf injury, will also miss the match at Balaidos.
Elsewhere, Luis Suarez's return from knee surgery was supposed to tip the title race in Barca's favour but the Uruguayan still looks a long way short of match fitness. He was slow and sluggish against Athletic.
Manager rating out of 10
6 -- Quique Setien cut a frustrated figure on the touchline at times as Barca struggled to break Athletic down and will have been hugely relieved to see his substitutes change the game. Both Puig and Fati had an impact after coming on, but it was Rakitic who scored the winning goal.
Player ratings (1-10; 10 = best, players introduced after 70 minutes get no rating)
GK Marc-Andre ter Stegen, 6 -- Dealt well with a difficult Unai Lopez cross shot in the fourth minute but didn't have many more stops to make after that.
DF Nelson Semedo, 5 -- A near ever-present in attack as Barca dominated possession but was unable to have an effect on the game. A first-half shot that dragged dreadfully wide was his most notable contribution.
DF Gerard Pique, 7 -- Good positioning throughout, and managed to keep the threat of the pacy Inaki Williams largely under control.
DF Jordi Alba, 6 -- Always an outlet on the left, getting forward and cutting back his trademark crosses. One in the first half could have been converted by Suarez.
MF Sergio Busquets, 7 -- A really intelligent performance. Brilliant play to prevent Williams in the first half and snuffed out a number of Athletic counters before they even reached Barca's half. Also came close to scoring from 25 yards, only to be denied by a brave Yeray Alvarez block.
MF Arturo Vidal, 6 -- A hard-working performance was almost capped with a stoppage-time goal on the volley, which Simon made a smart save on.
FW Lionel Messi, 7 -- The architect of most of Barca's best moves. Involved in Rakitic's goal and came close to scoring twice in the final stages, whipping two left-footers narrowly wide.
FW Luis Suarez, 5 -- Shot straight at Simon after a Antoine Griezmann dummy and sent another shot wide after a good Messi pass. Looks short of match fitness.
FW Antoine Griezmann, 6 -- One nice dummy and lots of nice runs, although he's often not used by his teammates. That said, Messi did use him in the 54th minute, but the chance went begging thanks to quick thinking from Simon.
MF Ivan Rakitic, 7 -- Made the difference with his first goal for Barca since March 2019, when he scored the Clasico winner in Madrid.
FW Ansu Fati, 7 -- Brought fresh legs and some pace to the left flank. Headed over the bar with his very first touch and shot against the post with his last.
MF Ricard Puig, 7 -- An energetic cameo off the bench helped to inject some enthusiasm into an aging Barca side.
FW Martin Braithwaite, N/R -- Replaced Suarez for final five minutes.