Bernardo Silva struck a second-half equaliser as Ligue 1 leaders Monaco were forced to settle for a 1-1 away draw against struggling Bastia.
The result sees Monaco edge into a four-point lead over champions Paris Saint-Germain, but Unai Emery's men - riding high from a 4-0 Champions League rout of Barcelona - can now gut the gap at the top to just one when they host Toulouse on Sunday.
Third-placed Nice, who are a further two points behind PSG, are at Lorient on Saturday.
Monaco came into the game with an astonishing 75 goals from 25 league matches, but they struggled for rhythm against second-bottom Bastia, who are now winless in seven games.
Hosts Bastia moved into a shock lead after 19 minutes, Sadio Diallo heading in Pierre Bengtsson's corner to score his first goal since October, despite goalkeeper Danijel Subasic's hopes he had saved before the ball crossed the line.
Monaco hit back seven minutes into the second half when Silva netted his fourth goal of 2017 with a header of his own, stooping low to convert Almamy Toure's cross.
Leonardo Jardim's men now switch their focus to Tuesday's trip to England, where they will face Manchester City in the first leg of their Champions League last-16 tie.