WIMBLEDON, England — Brad Gilbert, once a Wimbledon quarterfinalist and now, at 55, a commentator for ESPN, likes the current group of young U.S. women tennis players, and believes not too far in the future Madison Keys, now 21, will move to the No. 1 position that’s been held for so long by Serena Williams.

Keys, the No. 9 seed in this Wimbledon, the third American behind Serena (No. 1) and Venus Williams (8), was a 6-4, 5-7, 6-2 winner Saturday over France’s Alize Cornet.

“It would have nice to win in straight sets,” said Keys, “but it’s good to figure out tough situations and be able to play better, like in the third set.”

Two-time winner Petra Kvitova of the Czech Republic, the No. 10 seed, never got to a third set. She was beaten by Ekaterina Makarova of Russia, 7-5, 7-6 (5). “The short balls just killed me,” said Kvitova.

Two years ago Canadian Emile Bouchard was the finalist against Kvitova, and also reached the semis of the French and Australian, but her game has gone in reverse. Dominka Cibulkova of Slovakia defeated Bouchard, 6-4, 6-3, Saturday.

Angelique Kerber of Germany, No. 4 seed, winner over Serena Williams in the Australian Open final this winter, beat countrywoman Carina Witthoeft, 7-6 (11), 6-1, and very well could get to the final weekend.

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The men’s winners Saturday included No. 2 seed Andy Murray, now the tournament favorite with the loss by Novak Djokovic; American Steve Johnson, who beat Gregor Dimitrov, 6-7 (6), 7-6 (3), 6-4, 6-2, and Kei Nishikori, runnerup in the 2014 U.S. Open.

Serena fined. Serena Williams was one of three players fined for their actions and words during the first week. She was fined $10,000 for smashing her racquet during a second-round win over Christina McHale.

British No, 2 Heather Watson was fined $12,000 for jamming her racquet into the grass during a first-round loss to Annika Beck. And Victor Troicki, a Serb, was fined $10,000 for his rant — “You are the worst umpire in tennis,” he screamed repeatedly — against Damiano Torella in a first-round loss to Albert Ramos-Vinolas.