Lionel Messi suffered his first defeat as a Paris Saint-Germain player on Sunday as their perfect start to the Ligue 1 season ended with a 2-0 loss at Rennes while Marseille slumped to a loss on the day they mourned the death of controversial former president Bernard Tapie.
Messi smacked the crossbar with a free-kick in the first half at Roazhon Park before Gaetan Laborde volleyed Rennes ahead just before the break with his league-leading sixth goal.
"We didn't start the match well but then we played the best 25-30 minutes of the season. It's a shame we didn't score. We conceded two goals that were hard to take," said PSG coach Mauricio Pochettino.
PSG lost in the league for the first time since April, when they were beaten 1-0 at home by last season's eventual champions Lille.
Messi lined up alongside Neymar, Mbappe and Angel Di Maria for just the second match, making only his second league start for PSG after missing the past two Ligue 1 games with a knee injury.
Gianluigi Donnarumma again got the nod ahead of Keylor Navas in goal, having kept a clean sheet midweek in PSG's Champions League win over Manchester City.
Looking to keep pace with the team that won its opening 14 games under Thomas Tuchel in 2018, PSG created a series of chances midway through the first half -- all of which went to waste.
Neymar skied horribly after the ball broke kindly to the Brazilian inside the Rennes area and Mbappe was guilty of another glaring miss when he scooped over after getting in behind the home defence.
Messi, who bagged a spectacular first goal for PSG against City on Tuesday, nearly got off the mark in Ligue 1 but watched his curling free-kick from 25 yards clatter the bar on the half-hour.
PSG paid the price for their missed opportunities on the stroke of half-time.
Kamaldeen Sulemana whipped in a cross from the left which was thumped beyond Donnarumma by Laborde, a deadline day signing from Montpellier.
Rennes, who spent 80 million euros ($92.6 million) on new signings in the summer -- more than anyone in France including PSG -- caught the visitors cold right at the start of the second half to make it 2-0.
Laborde, released down the right, pulled back for Tait to sweep in first time -- the goal upheld after a VAR check for offside, and greeted by a deafening roar from a full house of close to 30,000 once it was confirmed.
PSG stay six points clear of second-placed Lens.
Hours after the death of former Marseille president Tapie at the age of 78, Jorge Sampaoli's side lost 2-0 at Lille as Jonathan David struck twice for the second league game running.
The Canadian moved level with Laborde at the top of the scoring charts after the Stade Pierre-Mauroy paid tribute to Tapie, the driving force behind Marseille's victory in the inaugural Champions League in 1993.
"RIP Boss," said a banner held up by Marseille fans.
There was no minute of applause or silence observed, but a photo of Tapie was displayed for a few seconds on the giant screens in the ground.
Marseille players wore black armbands as fans chanted Tapie's name. However, that prompted some hardline Lille fans to jeer.
"All the players had heard the news but we didn't talk about it, we just talked about the game plan we had to put in place," said Sampaoli.
Elsewhere, Aurelien Tchouameni scored against his former club to spark Monaco to a 3-0 victory over Bordeaux.
And Wahbi Khazri scored a stoppage-time penalty to give bottom club Saint-Etienne a 1-1 draw with local rivals Lyon for whom Houssem Aouar had scored in the first half.