Carlos Alcaraz admitted he had some pre-match nerves before taking to the court to play in the US Open mixed doubles event with Serena Williams on Tuesday.

Alcaraz, who is the reigning singles champion at Flushing Meadows, returned to competitive action for the first time since April after being sidelined by a right wrist injury. Playing in front of an estimated 15,000 spectators at Arthur Ashe Stadium, the Spaniard’s pairing with Williams was one of the event’s headline acts. In their opening match, the duo shook off some early rust to beat Great Britain’s Lloyd Glasspool and New Zealand’s Erin Routliffe 5-3, 4-1.

“I think everyone could see I was really nervous, I double-faulted on the first point,” Alcaraz said after the match.

“I was out for almost five months and I almost forgot how it feels stepping out on the court once again.

“It [took] just a couple of games [to settle] and she made it very easy for me to enjoy it and try to go for it.”

Williams, who won the US Open mixed doubles title four-and-a-half years before Alcaraz was born in 1998, utilised her usual powerful ball striking in what was the latest leg of her return to the Tour. She played at Wimbledon earlier this year but lost in the first round before suffering a knee injury that forced her to withdraw from the doubles event. She has played six matches across five events since June, with five of those being in doubles.

“It’s always amazing to be here. I never expected to be back on this court,” Williams said.

“It was just a really cool moment. I never thought this would happen.”

The high-profile pairing was stopped in their tracks in the quarter-finals by Flavio Cobolli and Belinda Bencic, who were the only seeded doubles team to reach the last four. The Italian-Swiss team battled through a close opener before sealing a 5-4(7-4), 4-1 victory. Earlier this year, Cobolli and Bencic won the Indian Wells mixed doubles event.

“To play with Serena, I never expected in my life,” said Cobolli. “But it was something incredible. I know that we [are from two] different generations, but she still is unbelievable on the court.”

“She tried to intimidate me before the match, but it didn’t work.” He later joked.

Alcaraz is expected to return to action next week in the singles draw, which will be his first event since the Barcelona Open.

Monfils kicks off last Grand Slam

Elsewhere, Gael Monfils and wife Elina Svitolina are also through to the semi-finals. Monfils is playing in his last US Open before retiring from the sport. His best singles result at the event was in 2016 when he reached the semi-finals.

“Today has been a great experience, obviously playing with Elina,” Monfils said. “For me definitely the first time and the last time.”

So far they have beaten Alexandra Eala and Felix Auger-Aliassime in the first round before battling past doubles specialists Katerina Siniakova and Henry Patten. Cobolli and Bencic awaits them next.

In the other half of the draw, Mirra Andreeva and Andreu Rublev won both of their matches by prevailing in a third-set 10-point tiebreaker.

“It’s true that we played really well, both matches,” Rublev said. “Mirra is something special, and I’m really happy to share the court with her.”

“We didn’t even prepare, we didn’t even do anything. But somehow it worked pretty well for us.” He added.

The Russian pair next faces Jakub Mensik and Karolina Muchova.

“I will say if we play under basically regular rules, until six games, it will be much more difficult,” Mensik said of the shortened format.

This year’s mixed doubles champions will earn $1,000,000 as a team in prize money.