With five games to go, Manchester City and Arsenal are only separated on goals scored at the top of the Premier League table.
"It's a new league now," says Gunners boss Mikel Arteta, whose side had been top of the table for 209 days until Wednesday.
Manchester City's 2-1 win over Arsenal on Sunday boosted their hopes - and a 1-0 victory at Burnley on Wednesday sent them top.
BBC Sport has got pundits, reporters and fans to predict a score for each club's five remaining games - to tell us who will be the champions.
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BBC Sport's Manchester City reporter Shamoon Hafez: "The handbrake is about to come off.
"With the title on the line, both teams will be free-scoring in the final five games of the Premier League campaign. They won't have flawless records - there will be a draw apiece and results will dictate both teams ending up with the same goal difference of +46. Although Manchester City have a tougher run-in than Arsenal on paper, their knowhow in terms of getting the job done during a tight race will prove crucial.
"We've had the Agueroooo goal, now we're about to see Semenyoooo doing similar. The Gunners will be leading against Crystal Palace on the final day of the season with one hand touching the Premier League trophy on goal difference.
"But City's January signing will score in injury time against Aston Villa to level the metrics and hand Pep Guardiola's side the title by virtue of scoring more goals than Arsenal, sparking wild celebrations at Etihad Stadium.
"It will allow City to complete a second domestic treble and a tearful Guardiola will sail off into the sunset after a decade of unprecedented success.
"Stranger things have happened in football, right?"
BBC Sport's Arsenal reporter Alex Howell: "Even though Arsenal have lost the momentum in the title race and have won just one of their past six games in all competitions, I still see them being champions at the end of the season.
"That's because Manchester City have a tougher run of games and I believe that Pep Guardiola's side will drop points too.
"I can see Mikel Arteta's side winning four of their five remaining league games with Manchester City drawing against Everton and Bournemouth, who are both chasing European football.
"There were positives for the Gunners even as they lost 2-1 to City last Sunday.
"Arteta selected Eberechi Eze and Martin Odegaard, who showed that they could be key in providing chances and a goal threat in an Arsenal attack that has increasingly looked short of ideas and fluidity in recent weeks.
"The title could be decided by goal difference depending on results and I think that Eze and Odegaard are going to have some big moments in deciding where the trophy ends up."
Former Celtic striker Chris Sutton predicts the outcome of all 380 Premier League games for BBC Sport - so he seemed an obvious choice to have his say on the title run-in.
"In the reverse fixtures, Arsenal beat all five of the teams they still have to play this season, by an aggregate score of 8-1. I think they will beat all five of them again," he said.