Eric Maxim Choupo-Moting was guilty of arguably the worst miss in the history of football as Paris St-Germain squandered the chance to wrap up the Ligue 1 title against Strasbourg.
Christopher Nkunku's shot was going in until former Stoke forward Choupo-Moting needlessly got a touch on the line and stabbed it on to the post.
PSG led through Choupo-Moting but Nuno da Costa levelled and Anthony Goncalves put the visitors ahead from 20 yards.
Presnel Kimpembe equalised for PSG.
But the capital side needed to beat Strasbourg to wrap up the title with eight games to go. They can seal it if they draw at second-placed Lille next Sunday.
Choupo-Moting had started ahead of 27-goal Ligue 1 top scorer Kylian Mbappe, who was rested but came on in the second half.
"I wondered if I was offside and it all happened very fast. I touched the ball, it hit the post and, well, it's a real shame because the ball was going in," Choupo-Moting told Canal+.
"Sorry about that."
They have won the cup four seasons in a row.
PSG, who have won five of the past six Ligue 1 titles, had won all previous 15 league home matches this season.