Gaston’s win, which was interrupted by rain with the players at 2-2 in the third set, propels him to a fourth-round match against U.S. Open champion Dominic Thiem, runner-up in the last two years at Roland Garros.
“It’s going to be a crazy experience,” said the 20-year-old Gaston, ranked 239th.
Wawrinka won the French Open in 2015.
In another third-round match, it took 36 points in a marathon third-set tiebreaker for Lorenzo Sonego to finally shake off the 27th-seeded American Taylor Fritz.
Sonego eventually won the tiebreaker in the 1-hour, 18-minute third set and the match 7-6 (5), 6-3, 7-6 (17).
He was among five Italian men in the third round at Roland Garros, an Open Era record at a Grand Slam.
There were shouts of “Bravo!” and “Merci!” filling the arena, fans in facemasks jumping up and down and an atmosphere sufficiently rowdy to forget how the coronavirus has taken huge bites out of crowd sizes at this year’s French Open when Caroline Garcia beat 16th-seeded Elise Mertens 1-6, 6-4, 7-5.
Garcia rode the partisan home support to advance to the fourth round and then told the crowd “there are not many of you but you make as much noise as when it’s full. I don’t understand.”
The match was played under the new roof on Court Philippe Chatrier. The revamped arena was built to hold 15,000 spectators but has been largely empty and eerily silent this year because of the limit of 1,000 spectators at the clay-court Grand Slam tournament.
Play resumed on outside courts after a rain-break as the 45th-ranked Garcia advanced to a fourth-round match-up against third-seeded Elina Svitolina.
Sebastian Korda also advanced. The son of 1998 Australian Open champion Petr Korda beat Pedro Martinez 6-4, 6-3, 6-1 in a rain-interrupted match.
Both men reached the main draw via the qualifying tournament. Korda is the first qualifier to reach the men’s fourth round since Alejandro Falla in 2011.
The French Open’s investment in the new roof over Court Philippe Chatrier is paying off again amid more rain.
Chatrier is the only arena at Roland Garros staying dry in a deluge that has stopped play on outside courts.
Rain pounding the clay-court Grand Slam tournament have sent spectators scurrying for shelter. The third-round match between Elise Mertens and Caroline Garcia on Chatrier is the only one that hasn’t been suspended. The 16th-seeded Mertens took the first set 6-1. The retractable roof has been closed over the court since the start of play.
All the other courts are covered with tarpaulins to stop the ochre surfaces of crushed brick dust from becoming soaked.
Simona Halep had no trouble reversing the result of her loss to Amanda Anisimova at last year’s French Open.
Halep won the rematch 6-0, 6-1 in just 54 minutes to reach the fourth round.
Anisimova made 32 unforced errors to Halep’s seven.
The top-seeded Halep extended her winning streak to a career-best 17 matches as she seeks a third Grand Slam title.
She won the trophy at Roland Garros in 2018.
Anisimova upset Halep in straight sets in the quarterfinals in Paris in 2019.
But this one went Halep’s way from the start thanks in part to the 19-year-old Anisimova’s inability to put her shots where she wanted.
Halep next faces another 19-year-old — Iga Swiatek.
U.S. Open champion Dominic Thiem advanced to the fourth round with another straight-sets win. He beat Casper Ruud of Norway 6-4, 6-3, 6-1.
Thiem was the losing finalist to Rafael Nadal at the last two French Opens.
Ruud was bidding to become only the second Norwegian to reach the fourth round of a Grand Slam. The first was his father at the Australian Open in 1997.
Christian Ruud now coaches his son and was watching in the largely empty Court Philippe Chatrier as Thiem earned a straightforward victory in 2 hours, 15 minutes under the new roof.
Thiem sealed the win with an ace. The 27-year-old Austrian was broken just once when he sent a forehand wide to give Ruud a 3-1 lead in the first set.
Thiem immediately broke back and converted six of his 15 break points in all. He also saved seven of the eight break points he faced.
Polish teenager Iga Swiatek advanced to the fourth round of the French Open for the second consecutive year with a 6-3, 6-2 win over Canadian wild-card entry Eugenie Bouchard.
The 19-year-old Swiatek has lost only 13 games so far at Roland Garros and not dropped a set. She opened her campaign with a first-round upset of 2019 French Open finalist Marketa Vondrousova.
Swiatek hit 30 winners and converted six of her 13 break points against the 168th-ranked and 2014 Wimbledon finalist Bouchard.
The 54th-ranked Swiatek lost to 2018 champion Simona Halep in the fourth round last year in her Roland Garros debut. She also made the fourth round at this year’s Australian Open.
Swiatek is the daughter of a former Olympic rower. Tomasz Swiatek rowed in the quadruple sculls at the 1988 Seoul Olympics.
Third-seeded Elina Svitolina of Ukraine also advanced. The two-time French Open quarterfinalist defeated Ekaterina Alexandrova 6-4, 7-5.
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