The last time Williams was eliminated this quickly at a major came in 2014, when she lost in the second round at Roland Garros then the third round at Wimbledon. Williams finished with 34 unforced errors, twice as many as Kenin.
In a match that included a lengthy discussion about whether a particular shot landed in or out, Juan Martin del Potro posted his first straight-sets win of the tournament.
Del Potro beat Jordan Thompson of Australia 6-4, 6-4, 6-0 to reach the fourth round and will next face 10th-seeded Karen Khachanov, who defeated Martin Klizan 6-1, 6-4, 6-3.
In the opening game of the third set, Thompson was awarded an ace on a break point despite protests over the ball mark from del Potro. However, del Potro went on to break anyhow and won the set with a bagel.
Also, last year's runner-up, Dominic Thiem, beat Pablo Cuevas 6-3, 4-6, 6-2, 7-5 and will next play home favorite Gael Monfils.
Monfils eliminated wild card Antoine Hoang 6-3, 6-2, 6-3 in an all-French matchup.
It was a day of upsets in men's doubles at Roland Garros with 16-time Grand Slam champions Bob and Mike Bryan, plus the top-seeded pairing of Lukasz Kobot and Marcelo Melo exiting in the second round.
The Bryan twins lost 6-3, 7-6 (7) to 10th-seeded Horia Tecau and Jean-Julien Rojer.
Kobot and Melo were beaten 5-7, 6-2, 6-3 by Fabrice Martin and Jeremy Chardy.
Mike Bryan said he and his brother didn't serve well enough — "and on clay, that's not going to cut it."
Mike added that his thoughts already were on Wimbledon, which starts l this month.
The French Open loss "is a shame," he said, "but you move on."
This was the Bryans' second major together since Bob returned from hip replacement surgery. They made the quarterfinals of the Australian Open in January.
The 41-year-old Americans have won a record number of Grand Slam trophies as a duo and more than 100 tour titles in all.
Top-ranked Novak Djokovic is into the fourth round of the French Open without dropping a set.
Djokovic never lost control in a 6-3, 6-3, 6-2 win over 147th-ranked Italian qualifier Salvatore Caruso and will next play either 13th-seeded Borna Coric or Jan-Lennard Struff.
Naomi Osaka's attempt at a third straight Grand Slam title is over.
The top-ranked player struggled throughout a 6-4, 6-2 loss to Katerina Siniakova in the third round of the French Open.
Siniakova is ranked No. 1 in doubles and No. 42 in singles.
The loss ends Osaka's run of 16 straight wins in Grand Slam tournaments— which included titles at the U.S. Open and Australian Open.
Stan Wawrinka improved to 4-0 against Grigor Dimitrov in Grand Slam meetings — beating him once at each major — and moved into the French Open's fourth round for the eighth time.
Wawrinka, the champion at Roland Garros in 2015 and runner-up in 2017, edged two-time major semifinalist Dimitrov 7-6 (5), 7-6 (4), 7-6 (8) in a match suspended after two sets because of fading light a day earlier.
Dimitrov certainly had his chances to make it even tighter: He held one set point in the opener, then five in the last tiebreaker, which he led 6-2.
The 24th-seeded Wawrinka, who owns three Grand Slam titles in all, and Dimitrov are the 43rd pair of players to have met at all four majors.
Simona Halep's title defense remains on track at the French Open following a methodical 6-2, 6-1 third-round win over 27th-seeded Lesia Tsurenko that lasted just 55 minutes.
Halep, whose only Grand Slam title came at Roland Garros last year, is bidding to become the first woman to defend a major since Serena Williams at Wimbledon in 2016
Halep's next opponent will be either Olympic champion Monica Puig or Iga Swiatek.
Tsurenko received treatment on her right leg during a medical timeout while trailing 3-0 in the second.
Serena Williams, Naomi Osaka and Simona Halep have had their rough patches so far in the French Open.
Those three stars are hoping for a smoother ride in the third round Saturday.
Williams continues her bid for a record-tying 24th Grand Slam singles trophy when she faces 20-year-old American Sofia Kenin. They have never played each other.
Kenin is trying to get to the fourth round of a major tournament for the first time. This is her ninth Slam appearance.
Osaka is now assured of retaining the No. 1 ranking, no matter what happens the rest of the way in Paris. She can get to the round of 16 at Roland Garros for the first time by beating Katerina Siniakova.
Defending champion Halep opens the day's schedule in Court Philippe Chatrier against No. 27 seed Lesia Tsurenko.
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