Dani Alves’ wonderful opener was cancelled out by defender Diego’s brace and Abdul Majeed Waris’ strike as Nantes took control. Metehan Guclu then scored a late consolation.
PSG remain 17 points clear at the top of the table and host Monaco on Sunday.
Boss Thomas Tuchel rejected suggestions the club were in crisis after the 5-1 thrashing against Lille and they were on course for the title when Alves brilliantly opened the scoring in the 19th minute.
The defender collected the ball 30 yards out and unleashed a swerving strike which dipped into the top corner.
But the visitors’ lead was short-lived when Diego levelled just three minutes later.
Poor defending allowed the centre-back to power in a header from captain Valentin Rongier’s corner.
Waris made it 2-1 a minute before half-time when he tapped in at the far post following good work from Kalifa Coulibaly and Samuel Moutoussamy.
Diego then grabbed his second seven minutes after the re-start, fortuitously scrambling in from a corner.
Eric Choupo-Moting hit the post for PSG before Guclu pulled a goal back with a minute left.
*Copy provided by Press Association Sport
Kylian Mbappe claimed Paris St Germain “played like beginners” after they suffered their heaviest Ligue 1 loss in 18 years on Sunday.
Needing to avoid defeat to seal the title, PSG instead suffering a humbling 5-1 reverse to second-placed Lille, collapsing in the second half after the dismissal of Juan Bernat.
Bernat had cancelled out Thomas Meunier’s own goal in a first half that saw Mbappe twice denied for offside, but once down to 10 men, PSG conceded efforts to Nicolas Pepe, Jonathan Bamba, Gabriel and Jose Fonte.
“It was an end-to-end match,” Mbappe told Canal Plus.
“One moment we were on top, the next we were not. We can afford to lose, we will still be champions, but we cannot lose like this, not with three, four or five goals conceded.
“We must play with more personality. This is a problem we must correct.
“Football is played on the pitch. It is not about just saying things. We played like beginners and we must not lose like that.”
Coach Thomas Tuchel disagreed with his striker, and pointed to a long list of absentees which grew with Thiago Silva and Meunier hobbling off in the first half.
“We did not play like beginners – it is too easy to say that,” he said in his post-match press conference. “We scored three goals against Lille but two were offside.
“There were no chances for Lille in the first half, and we had an opportunity to score a second goal.
“Moussa Diaby has played only twice and (Thilo) Kehrer is sick – ordinarily they should not be with us, but here we are.
“Bernat played on the left, then the middle, it’s not normal. It shows the extraordinary mentality we have had, but it’s too much.
“Marquinhos is sick, Thiago Silva is injured. Lille are a fantastic team and with 10 men it was complicated but we played well.”
Tuchel admitted he may struggle to put out a side against Nantes with Marco Verratti picking up a booking to earn a suspension, adding to that facing Bernat.
While PSG lick their wounds, Lille are getting used to the idea of Champions League football after moving eight points clear of Lyon in second place.
Victory for the reigning champions would have seen them retain their Ligue 1 crown on Sunday night, after second-placed Lille’ 1-1 draw at Reims earlier in the day.
Despite a host of injury problems and the absence from the starting line up of Neymar, Edinson Cavani and Kylian Mbappe, who was named as a substitute, it looked a formality when Eric Maxim Choupo-Moting scored after 13 minutes to put PSG ahead.
However, Strasbourg arrived in the French capital on a high after winning the Coupe de la Ligue final last weekend and following it up with a 4-0 midweek success against Reims, and the visitors rallied.
Thierry Laurey’s team turned the game on its head before half-time with goals from Nuno Da Costa and Anthony Goncalves.
PSG should have regained the lead immediately after the visitor’s equaliser, but an astonishing miss by Choupo-Moting meant it stayed level. Christopher Nkunku lifted his shot over the advancing goalkeeper and the ball was set to trickle into the net, only for Choupo-Moting to follow it in and stop the ball on the goal line in an attempt to get the final touch and his second goal of the game.
Chupo-Moting 🤯 nearly as bad as Nani stopping one of the greatest goals of all time in a Portugal-Spain game because he headed it in (it was already going in) on the goal line (and he was offside) pic.twitter.com/50BkzXAzDe— Tommy Rooney (@TomasORuanaidh) April 7, 2019
Thilo Kehrer equalised with eight minutes remaining, but the hosts could not find a winning goal and their inevitable coronation was put on hold.
However, all the talk was about Choupo-Moting’s miss.
Check out the video above to see what PSG boss Thomas Tuchel had to say about his misfiring striker.