Arsenal's Leandro Trossard capitalised on dreadful defending to secure a 1-0 win against Manchester United that saw the Gunners climb back to the top of the Premier League, ensuring the title race will be decided on the final day.
While Arsenal, who won for just the second time at Old Trafford in their last 17 visits, have 86 points with one game left of the tightest title race in years, holders City remain in the driving seat with 85 points and two matches to play.
City, who are aiming for an unprecedented fourth consecutive English top-flight title, can retake the lead if they beat Arsenal's London rivals Tottenham Hotspur on Tuesday.
"I am going to be the biggest fan of Tottenham ever," Arsenal's Kai Havertz told Sky Sports. "Let's hope for the best.
"We didn't have our best game but we needed the three points and we have it now so we can be happy. We have to win every single game as City are always keeping the pressure on," he added. "It is so nice to be in the race and every week you have to play at your best. When you do it, it feels even better."
Trossard scored in the 20th minute when Havertz sauntered barely challenged into space on the right before sending the ball into the box for Trossard to tuck home.
Heads turned to check for an offside flag but Casemiro, recently moved from midfield into United's injury-depleted back line, had slowly moved out from the box and kept Havertz onside after goalkeeper Andre Onana launched the ball upfield.
United manager Erik ten Hag was left shaking his head in frustration.
"Obviously we only have one objective to win the league," Trossard told Sky. "We have done our job today and it will be up to the last game and that is what we are aiming for."
The game swung from end to end over a final tense few minutes, with Onana leaping to push away shots from Arsenal substitute Gabriel Martinelli and Declan Rice.
United, who were hoping to bounce back after a woeful 4-0 loss at Crystal Palace are eighth with two games left. They trail sixth-placed Newcastle by three points in their quest for a European berth next season, setting up a key showdown when the Magpies visit Old Trafford on Wednesday.
Ten Hag said it would be "very damaging" to miss Europe.
United have now conceded 82 goals this season in all competitions -- their most in a single campaign since 1970-71.
Arsenal host Everton in their season finale, while Man City are at home to West Ham United.