Two major challengers to Serena Willams fade out at U.S. Open

After Serena Williams beat her sister Venus, talk at the U.S. Open turned to who might be able to derail Serena’s Grand Slam quest.

The quick, easy — and likely correct — answer was: nobody.

The leading candidates seemed to be Petra Kvitova of the Czech Republic, a two-time Wimbledon champion, and Victoria Azarenka of Belarus, a two-time Australian Open champion and twice a loser in the finals here to Williams.

Then, in their quarterfinals Wednesday, the leading candidates lost.

Kvitova, with a big left-handed serve and deep strokes that seemed a threat to Williams, faded badly in a third set and lost to Flavia Pennetta of Italy, 4-6, 6-4, 6-2.

Azarenka, with a big enough game to test Williams and a feisty, fist-pumping demeanor that, occasionally, has her busting up locker-room chairs, got busted herself in a rain-delayed, 2-hour 40-minute battle.

This time, the screaming Azarenka was more sound than fury. She lost, 6-3, 4-6, 6-4, to second-seeded Simona Halep, who knew who to thank for her victory.

“I was a bit tired after the second set,” Halep said, “so the break helped me. Thank you, God.”

The rain delay was 1 hour 25 minutes.

Halep clearly knew what she was up against in Azarenka, who was seeded 20th but had played with the kind of fire that led many to believe she would be the toughest final hurdle for Williams.

“She is a fighter girl,” Halep had said of Azarenka.

In response to a question about Halep’s improved form since bad outings at the French and Wimbledon, Azarenka said: “I don’t usually get them when they are in bad form. Usually, they play really well against me.”

Halep, a Romanian, will be the youngest and shortest of the remaining three players in the quest to be the Serena spoiler. She is 5 feet 3 and won’t turn 24 until Sept. 27.

Williams’ semifinal opponent, Italy’s Roberta Vinci — given only a slight chance because of her funky slice and mixed-pace game — is 5-4 and 32. Halep’s semifinal opponent, Pennetta, is 5-8 and 33. Williams is 5-9, plays about 6-6, and will turn 34 on Sept. 26.

That means the U.S. Open women’s semifinals, always an ultimate test of endurance and physical fitness, ended up with three of its four competitors older than 30. Two of them are Italian.

Pennetta gave her fellow compatriot a chance against Williams, but her rationale sounded more hopeful than constructive.

“…Of course she has a chance tomorrow,” Pennetta said. “I mean, she has to go on the court and try her best. She doesn’t have anything to lose. She has in front of her Serena Williams.”

Pennetta said she saw her advantage over Kvitova in that final set, on yet another hot and humid day in New York.

“Physically, I was better than her in the last set,” Pennetta said. “So that was the difference for sure.”

Kvitova didn’t disagree, but was not specific as to the cause.

“I was kind of hot out there today,” she said. “Energy-wise [this] wasn’t probably the best today.”

Later, when asked whether she will be able to play on the women’s tour in Asia, she said, “I really don’t know. I’m coming back to make some blood test(s) … now I’m feeling really exhausted ... I really have no idea. I’m going to talk with the doctors again.”

Azarenka converted all five of her break points. She just didn’t get enough of them. Halep got 19 and converted six.

Pennetta was a model of consistency, as she usually is. She had 16 unforced errors, Kvitova had 60.

Notes

A U.S. men’s doubles team of Sam Querrey and Steve Johnson, who eliminated the top-seeded Bryan brothers in the first round, kept going with a 6-3, 6-4 advance into the semifinals over Leonardo Mayer and Joao Sousa, 6-3, 6-4. The winners might as well have dressed in cardinal and gold. Johnson led USC to four NCAA titles before turning pro and Querrey made an oral commitment to the Trojans, but turned pro instead.… Rancho Santa Fe’s Taylor Fritz, top seeded in the junior boys’ singles, advanced to the quarterfinals.

bill.dwyre@latimes.com

Twitter: @DwyreLATimes