Czech Karolina Pliskova blew past Croatian teenager Ana Konjuh 6-2, 6-2 on Wednesday to reach the semifinals of the US Open.

Tenth-seeded Pliskova, who survived a match point in her fourth-round victory over sixth-seeded Venus Williams, will face either world number one Serena Williams or fifth-seeded Romanian Simona Halep for a place in Saturday's championship match.

"I'm so excited to be in my first semi-final," said 24-year-old Pliskova, who had failed to make it out of the third round in 17 prior Grand Slam appearances.

Having broken through to the quarters she didn't waste her opportunity.

With a quick break under her belt in the opening game she was able to swing freely and needed just 57 minutes to subdue Konjuh, who upset fourth-seeded Agnieszka Radwanska in the fourth round.

“I think it was the serve," said Pliskova, who finished off the match with two of her three aces. "My serve was very good today.”

Meanwhile, defending champion Novak Djokovic booked a 10th straight semifinal appearance when Jo-Wilfried Tsonga retired trailing 6-3, 6-2 in their marquee quarter-final on Tuesday.

It was the third time in five matches that an opponent's injury has worked to Djokovic's advantage, after his walkover into the third round where Mikhail Youzhny retired after just six games.

Ninth-seeded Tsonga gave him more of a workout, but even before an apparent left knee injury began to trouble the Frenchman in the second set Djokovic had the match well in hand.

The Serbian world number one will face another Frenchman, Gael Monfils, for a place in Sunday's championship match after the 10th seed pummelled compatriot Lucas Pouille 6-4, 6-3, 6-3.

It was the first time in 89 years that three French men had reached the quarter-finals of the US championships.

Monfils was in control throughout against the 22-year-old Pouille, who was coming off an epic fifth-set tiebreaker win over 14-time major winner Rafael Nadal.

That marked the 24th-seeded Pouille's third straight five-setter. Whether it was a let-down after the biggest win of his career or sheer fatigue, his 44 unforced errors meant he never stood a chance against a dialed-in Monfils.

Pouille conceded a break with a stream of errors to fall 1-2 down in the second, and a break of more than 15 minutes to close the new Arthur Ashe stadium roof, with Monfils up 4-3, did nothing to change the momentum.

After holding with back-to-back aces, Monfils broke the error-prone Pouille at love to take the set.

One break was all he needed in the third, as he wrapped up the match without facing a break point.

Caroline Wozniacki's dramatic resurgence continued when the former world number one defeated a hobbling Anastasija Sevastova to reach a fourth US Open semi-final.

The two-time runner-up, ranked at a lowly 74 after an injury-hit campaign, eased to a 6-0, 6-2 win and will face second seed Angelique Kerber for a place in Saturday's championship match.