Substitute Souleymane Camara grabbed a dramatic stoppage-time equaliser as Monaco were held to a 1-1 home draw by Montpellier and missed the chance to go top of Ligue 1.
Champions Monaco did not produce a vintage performance on Friday, but Radamel Falcao's 12th goal in eight league games, scored seven minutes before the break, continued a stunning individual start to the season for the striker and looked like it would prove decisive.
But Monaco failed to build on that lead and Camara headed home in the second minute of stoppage time to grab a draw that Montpellier deserved.
Failure to win means Monaco remain behind title rivals Paris Saint-Germain on goal difference ahead of Unai Emery's men facing Bordeaux on Saturday.
12/13 - Falcao has scored 12 goals from just 13 shots on target in Ligue 1 in 2017/18. Tiger.-- OptaJean (@OptaJean) September 29, 2017
It was another blow for Leonardo Jardim's men after their morale-denting 3-0 Champions League loss to Porto last time out and only the second time in 22 home league games they had failed to win, in a run stretching back to last season.
Montpellier, meanwhile, add to their surprise draw against PSG last week and move up to 10th after an impressive performance.
Underdogs Montpellier were in control for much of the first half, Isaac Mbenza curling a 20-yard free-kick inches over with their first opportunity of note.
The visitors should have been in front when they seized on slack Monaco passing to produce a well-worked move that resulted in an unmarked Stephane Sessegnon firing over after being set up by Jerome Roussillon.
Pedro Mendes then cut inside from the right and forced a low save from Danijel Subasic, who was making his 150th Ligue 1 appearance in the Monaco goal.
But against the run of play, it was the hosts who moved in front. Rony Lopes raced down the right and played in perfect low cross which a stretching Falcao turned in at the far post, goal-line technology showing the ball had just crept over the line before Benjamin Lecomte got back to save.
The second half was a much quieter affair, with the first significant chance not arriving until Ruben Aguilar volleyed narrowly wide after Roussillon's cross from the left flicked into his path.
Monaco could have wrapped up the points when Thomas Lemar was caught in two minds after being played in, the France international failing to hit the target with a poor finish.
And the hosts were stunned in stoppage time when Hilton's high ball was nodded on by Kevin Berigaud to fellow sub Camara, who headed past Subasic from eight yards to silence Stade Louis II.