NEW YORK -- American Madison Keys breezed past reigning Wimbledon champion Marketa Vondrousova 6-1, 6-4 on Wednesday night to reach the US Open semifinals, fending off all nine break points she faced.

Keys, a 2017 US Open finalist, suffered a handful of early exits at Flushing Meadows in recent years but has excelled in the 2023 tournament and appeared right at home in prime time under the bright lights of Arthur Ashe Stadium.

Vondrousova, the No. 9 seed, withdrew from her doubles campaign after a three-set test from American Peyton Stearns in the fourth round left her with a sore arm, and she had little firepower left for the quarterfinal affair.

"I just love it here. I love playing here. In front of a home crowd you can never feel like you can't get out of any situation," said Keys, who advanced to her sixth major semifinal and third at the US Open (2017, '18). "I knew I was going to have to keep trying to get to the net, be aggressive."

Keys next faces No. 2 seed Aryna Sabalenka, who dispatched China's Zheng Qinwen in another lopsided performance on Ashe earlier Wednesday.

"It's going to be a lot of hard hitting, not a lot of long points," said Keys, who lost to Sabalenka at Wimbledon in July. "Just going to try to buckle up and get as many balls back as I can."

The other women's semifinal will be No. 6 Coco Gauff against No. 10 Karolina Muchova; they won their quarterfinals Tuesday. The last time two American women made the semifinals at the US Open was 2020 (Serena Williams and Jennifer Brady).

Keys vs. Vondrousova was interrupted for eight minutes in the first game when a spectator in the lower level needed medical attention. Keys brought two towels and a bottle of water over to where the fan was being helped. The U.S. Tennis Association said the episode was not heat-related.

Keys was clearly not rattled by the incident and took control once play resumed, breaking Vondrousova to love in the second game and converting on another break point chance with a fine forehand winner in the fourth.

Vondrousova upped her level across the board in the second set, improving her serve considerably, but was unable to seize any momentum and instead was left to rue missed opportunities as she failed to convert on five break points in the eighth game alone.

Keys broke her opponent in the ninth game and let out a cheer as she forced Vondrousova into a backhand error on match point.

The Associated Press and Reuters contributed to this report.