Rennes had not won a trophy since 1971 and it showed. Keeper Tomas Koubek hared wide-eyed down the touchline; Hatem Ben Arfa was in tears; sporting director Olivier Létang booted balls into the crowd; Clément Grenier cramped up chasing Koubek; and 30,000 Bretons erupted at the end of a raucous night at the Stade de France. Amid a downpour in Paris, the cup of shocks produced one of its most memorable upsets as PSG were embarrassed again, a talented young manager triumphed and Ben Arfa had his revenge.

Incredibly, PSG had been 2-0 up. Dani Alves gave them the lead in the 13th minute, volleying Neymar’s corner past Koubek à la Beckham and Scholes. Neymar doubled the lead with a cute dink eight minutes later. It looked like the rest of the match would be a formality, but Presnel Kimpembe’s sliced clearance flew past Alphonse Areola just before half-time to give Rennes hope.

During the interval, Rennes coach Julien Stéphan “sensed there could be fragility and nervousness from the opposition,” he explained afterwards. “We had to press on, believe in ourselves and, above all, remain coherent in our gameplan.” His plan to contain and counter played out perfectly. PSG were unable to capitalise on their possession and Rennes remained a threat, with centre-back Mexer heading home an equaliser midway through the second half.

With penalties looming, Kylian Mbappé, who had wasted several clear openings, was sent off for a horrible challenge on Damien Da Silva. The wild tackle on the defender’s knee again underlined the darkening of Mbappé’s mood and the shortening of his temper since he joined PSG two years ago. He is not the grinning, joyful teenager from Monaco anymore.

PSG took the surprising choice to go second in the shootout and, after six unerring penalties from Rennes, Christopher Nkunku – who has spoken to Rennes about a move in the summer – needed to score his spot-kick to keep PSG’s hopes alive. His high, wayward attempt sparked pandemonium. “This is a dream,” said Rennes owner François-Henri Pinault. “When I was young I was a ball boy here. I am proud, emotional.”

Tuchel, however, was at a loss. “It’s too early to do a postmortem,” said the PSG manager. “I’ll have to think for several days. We have to be honest with ourselves. This is not an easy situation. We lost our intensity after the winter break.” The German also suggested his players had been complacent. “We lacked the instinct to go and get the third or fourth goal. We tried to do things that are harder, but you don’t do that in decisive games. We were not aware that it is always possible to lose your confidence and to lose the match.”

Play Video 0:34 Neymar appears to 'punch at a fan goading him' after PSG's shock cup final defeat – video

Neymar – who struck a Rennes fan who had supposedly insulted him on the walk to collect his runners-up medal – criticised his more inexperienced teammates. “They need to listen more than they talk,” said Neymar. “Sometimes when a more experienced guy speaks, they answer back. When the coach speaks, they answer back. This is not how the team will go far.”

Stéphan, meanwhile, praised his team’s “organisation, courage, self-sacrifice and technical quality.” While Rennes’ win was a shock, Stephan’s success is not. Since his appointment in December, he has squeezed the best from his players and earned their admiration. Joris Gnagnon, who worked under Stéphan in the Rennes youth team before moving to Sevilla last summer, says Stéphan was “the father I didn’t have. He educated me as a man and as a footballer. I struggled with authority but when Julien spoke to me, it was different. I managed to channel myself.”

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“This title will change the history of the club,” said Stéphan – and he could be right. Stéphan’s men gave Arsenal a scare in the Europa League and beat Lille and Lyon (second and third in Ligue 1) on their run to the cup final. Back in Europe with an inspirational, intelligent young coach and a dynamic, talented squad, Rennes could be poised to establish themselves as regular challengers in France. The club have invested a lot of money in Ismaïla Sarr, Grenier and Ben Arfa, and Stéphan can expect more support this summer.

Few will enjoy this triumph more than Ben Arfa, who was exiled at PSG after he publicly criticised the board. This was redemption for the 31-year-old. Eighteen months on from sarcastically posing with a “birthday cake” having not played for PSG for an entire year, he says winning the cup is “the most beautiful title of my career.”

The celebrations carried into the night in Rennes, where thousands gathered in the Esplanade Charles de Gaulle as their heroes were presented the cup. Against all odds, Rennes had produced another “remontada”, said a victorious Haten Ben Arfa. “But”, he explained, “PSG are used to that.”

Facebook Twitter Pinterest Hatem Ben Arfa enjoys the moment. Photograph: Damien Meyer/AFP/Getty Images

Ligue 1 talking points

• It is not often that Nice score more than the odd goal. Before their 3-0 win over Guingamp on Sunday, Patrick Vieira’s side had the poorest attack in the division. Putting three past the bottom side in the league is not exactly a surge in their attacking form, but the nature of the win will have turned some heads, as Youcef Atal doubled his total for the season with a hat-trick. He was initially played as a right-back, but Nice’s switch to a 4-3-3 in recent weeks has seen him played further forward to make better use of his ability on the ball, a switch that has paid great dividends. Signed for €3m in the summer, Atal’s value has increased at least five-fold. He is following the likes of Ricardo Pereira and Dalbert in the club’s impressive recent run of full-backs.

• Robert Beric helped Saint-Étienne keep the pressure on Lyon with a brace in a resounding 2-0 win over Toulouse. Seemingly on his way out after the acquisition of Loïs Diony last summer, the Slovenian impressed upon returning from a loan at Anderlecht last season and has continued in this vein. He now has four goals in his last three starts and his form has been key for Saint-Étienne as Wahbi Khazri (one goal in his last 11) appears to be in the throes of his habitual post-Christmas slump.

• Finally, Memphis Depay was on the scoresheet for the second week running, helping Lyon to a 3-2 win at Bordeaux. The Dutchman, who appears to have more than one foot out the door amid reports that he has moved out of his house and into a hotel, had not scored in consecutive matches since October. Regardless of his own feelings about still being in Lyon, the club and their supporters are surely happy to have him on the upswing as they continue to stay just ahead of their rivals in the race for third place and the final Champions League spot.

Quick guide Show Hide Ligue 1 results Bordeaux 2-3 Lyon

Amiens 0-0 Strasbourg

Angers 1-1 Reims

Caen 1-0 Dijon

Lille 5-0 Nîmes

Nice 3-0 Guingamp

Saint-Étienne 2-0 Toulouse

Marseille 1-2 Nantes

Ligue 1 table