Follow The Athletic’s French Open coverageWelcome to the French Open briefing, where The Athletic will explain the stories behind the stories on each day of the tournament.On Day 3, a 17-year-old local thrilled the Roland Garros crowd, Aryna Sabalenka stuck to her script, and Coco Gauff had an interesting morning.How did a 17-year-old talent bring home cheer?It’s been a tough few days for French tennis fans and players at their home Grand Slam.They lost their talisman, 39-year-old Gaël Monfils, who fell in five sets Monday night in his final French Open appearance.Their rising star, 21-year-old Arthur Fils, withdrew the day before the tournament started with an injury. Fils had to withdraw from last year’s tournament with injury, too, after two thrilling wins.Loïs Bosson, 23, last year’s Cinderella story, the wild card who barreled her way onto the semifinals, lost in the first round in the midst of an injury-riddled season.Moise Kouamé to the rescue.Kouamé, 17, became the youngest man to win a Grand Slam match in 17 years when he knocked off Marin Čilić in straight sets to kick off the day on Court Simonne-Mathieu. His win was close and then not close as all. He edged Čilić, the 2014 U.S. Open champion, in a first-set tiebreak, then rolled in a 7-6(4), 6-2, 6-1 win.Kouamé, who hails from Sarcelles, one of Paris’ northern banlieues, was emotional on the court in front of a delirious crowd. He won a tour-level match at the Miami Open in March, but his first major win was a tonic to a tournament in need of some zip — and some French success. It made him the first male player born in 2009 to win a Grand Slam match.Kouamé, whose coach is Monfils’ contemporary, Richard Gasquet, doesn’t want to stop there.“Is a good achievement,” he said of the win in his news conference. “Of course the most important is ahead. So now the head is focused on recovering and be ready as much as possible for the next round.”He will have a decent shot. He faces Adolfo Daniel Vallejo of Paraguay, the world No. 71, on Thursday.France will be watching, and hoping.— Matt Futterman