Gael Monfils overwhelmed fellow-Frenchman Lucas Pouille 6-4 6-3 6-3 to become the first man into the semifinals of the US Open on Tuesday, while Novak Djokovic's easy run continued as another opponent retired.
Tenth seed Monfils was his energetic, athletic self and invincible from the service line in a commanding win over 22-year-old Pouille, who was coming off three successive five-set wins including a fourth-round upset of 14-times slam winner Rafa Nadal.
The 30-year-old Monfils finished off 24th seed Pouille with his 13th ace to lead off a huge day for the French, who placed three players in the quarter-finals of a grand slam for the first time since the 1947 French Open.
Monfils, who reached his second career grand slam semi-final and first since 2008 in Roland Garros, will now meet top seed Djokovic.
The Serb advanced after ninth-seeded Frenchman Jo-Wilfried Tsonga retired at the start of the third set of their quarter-final, trailing 6-3 6-2.
Tsonga took a medical timeout during the changeover at 5-2 of the second set and had the area below his left knee taped.
World No 1 Djokovic held serve at love to close out the set for a 6-3 6-2 lead but the Frenchman walked off to give the Serbian passage into the U.S. Open last four for the 10th consecutive time.
It has been a strange slam for Djokovic, who has played only two full matches in the tournament, gifted by a walkover in the second round and a retirement after six games in the third round before his abbreviated match with Tsonga.
Monfils has yet to beat Djokovic in 12 career meetings.
Kerber, Wozniacki dominate
Second seed Angelique Kerber was first through to the semis, bringing Roberta Vinci's dream run to an end with a clinical 7-5 6-0 win on Tuesday.
The match had looked an intriguing one between the German, who is eyeing Serena Williams's world No 1 ranking, and the 33-year-old Italian Vinci, who discovered a fountain of youth at Flushing Meadows last year where she reached the finals.
But a foot fault on set point in the opening set appeared to trip up Vinci and sent her tumbling out of the year's final grand slam.
Three times Vinci would break Kerber in the opening set and three times she would allow the German to immediately break back, including once while serving at 5-4 for the set.
But it would be Kerber claiming the decisive break to win the set when Vinci was called for a foot fault on her second serve before sarcastically applauding the line judge as she walked off the court.
The Italian never recovered and Kerber blasted through the second set in 24 minutes to clinch her semi-final spot where she will face the winner between Denmark's Caroline Wozniacki and Latvian Anastasija Sevastova.
Former world No 1 Caroline Wozniacki eased into the next round with a ruthless 6-0 6-2 win over a wounded Anastasija Sevastova.
Sevastova, the first Latvian to reach a grand slam quarter-final, rolled over her ankle chasing down a ball on Wozniacki's opening serve and was unable to challenge her Danish opponent despite bravely fighting on until the end.
With her opponent hobbled, Wozniacki showed no mercy and moved in for the kill, keeping Sevastova running from sideline to sideline. She next meets Kerber.
