PARIS — Juan Martin del Potro frittered away four chances to claim a gripping first set against No. 1 Andy Murray on Saturday at the French Open, including a double fault in the tiebreaker.

Then, on Murray's third set point, del Potro made another mistake, pushing one of his intimidating forehands wide. After walking up to check the ball’s mark on the clay, del Potro leaned forward on the net, head bowed, the very picture of despair.

Eventually, del Potro went to his sideline seat and covered his face with a towel. That set was gone, and soon enough his first appearance since 2012 at Roland Garros would be over with a 7-6 (8), 7-5, 6-0 third-round loss to Murray.

“Too much frustration,” said del Potro, the 2009 U.S. Open champion, who has endured a series of operations on his left wrist, making two-handed backhands problematic. “I couldn’t believe I lost that set.”

Neither, really, could Murray, who noticed how crestfallen his opponent was after that vital set. It lasted nearly 11/2 hours.

“Look, regardless of how someone reacts, necessarily, you still have to expect that they are going to come out and start the (next) set strong,” Murray said.

But under a cloud-filled sky, Murray was looking more and more like the top-ranked player he is.

“I’m starting to feel better,” Murray said. “I had struggled the last six or seven weeks.”

After the rematch of the 2016 Rio Olympics final he won, Murray declared the last two sets “definitely” the best he’s played on clay this season. His major titles have come on faster surfaces at Wimbledon and the U.S. Open, but Murray was the French Open runner-up last year.

The 2015 champion in Paris, Stan Wawrinka, joined Murray in the fourth round with a 7-6 (2), 6-0, 6-2 win over 28th-seeded Fabio Fognini. Next up for Wawrinka: No. 15 Gael Monfils or No. 24 Richard Gasquet, a pair of Frenchmen whose match was suspended because of rain.

Other men advancing before the downpour: 2014 U.S. Open champion Marin Cilic, Kevin Anderson and Fernando Verdasco.

Victories by Alize Cornet and Caroline Garcia gave France three women in the fourth round of the French Open for the first time since 1994 after Kristina Mladenovic advanced Friday.