Stade Rennes rallied from two goals down to stun Paris St-Germain 6-5 on penalties in the French Cup final after a 2-2 draw on Saturday as the Ligue 1 champions' season heads for a gloomy finale.

Thomas Tuchel's side, French Cup winners for the last four years, were 2-0 up after 22 minutes following goals by Dani Alves and Neymar, only for Presnel Kimpembe to score an own goal before Mexer equalized to send the game into extra time.

PSG's France striker Kylian Mbappe was sent off two minutes before the end of the extra period, depriving his team of a key asset for the shootout.

Christopher Nkunku missed his spot kick to hand Rennes their first cup title since 1971 and a spot in next season's Europa League, leaving PSG with only the Ligue 1 trophy at the end of a season in which they exited the Champions League at the last-16 stage and lost their League Cup crown.

A week after making his comeback from a three-month injury layoff, Brazil forward Neymar was a constant threat as he gears up for the Copa America, but his teammate Mbappe lost his nerve ­after a disappointing night at the Stade de France.

Rennes, who eliminated Lille and Olympique Lyonnais en route to the ­final, looked out of sorts after conceding two early goals but Kimpembe's own goal put them back into contention and proved a turning-point in an entertaining game.

"It's an outstanding performance, the fans had been waiting for this for such a long time," said Rennes striker Mbaye Niang. "We showed character, it's a deserved win."

Tuchel struggled to understand the loss.

"It's hard to explain, I have no explanation. We lost our concentration," he told a news conference after PSG failed to win multiple trophies in a season for the first time since 2012-13.

"It's too soon to assess our season, I need a few days to think about it."

PSG choked in key moments this campaign, knocked out of the Champions League by Manchester United after building a two-goal advantage at Old Trafford and thrashed 5-1 at second-placed Lille on a night they were hoping to seal the Ligue 1 title.