STAR pairing Serena Williams and Carlos Alcaraz defeated Britain’s Lloyd Glasspool and his partner Erin Routliffe before losing in the quarter-finals of the US Open mixed doubles.

Williams — a 23-time grand slam singles champion — made her return to tennis in June at the age of 44, while seven-time major winner Alcaraz, 22, had been off the tour since April nursing a wrist injury.

The high-profile duo embraced after capitalising on a third match point at Arthur Ashe Stadium to secure a 5-3 4-1 victory in just under an hour.

“I never expected to be back on this court,” said Williams, according to usopen.org. “It’s just a really cool moment — I never thought this would happen.”

Alcaraz double-faulted on the first point en route to dropping the opening service game and admitted to feeling some nerves.

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

“She [Williams] made it really easy for me — just to try to enjoy it and go for it every time.”

Williams and Alcaraz were subsequently denied a semi-final spot by a 5-4 (4) 4-1 loss to fourth seeds Flavio Cobolli and Belinda Bencic.

Earlier, top seeds Novak Djokovic and Aryna Sabalenka suffered a first-round exit after surrendering a one-set lead to lose to Britain’s Henry Patten and Czech player Katerina Siniakova.

Patten and Siniakova — two of the world’s top-ranked doubles players — overcame some early nerves to complete a 1-4 4-2 10-2 comeback victory.

Djokovic — a 24-time grand slam singles champion, including four US Open titles — was aced by Siniakova on match point in the tie-break.

Patten, 30, told Sky Sports: “It wasn’t looking very good for a while. In this format, we played one bad game and all of a sudden the first set’s gone.

“We knew the same was possible in the second set and we played an amazing tie-break — Kat acing Novak on match point was pretty fun.”

Patten and Siniakova were later beaten 5-4 (6) 4-5 (3) 10-8 by married couple Gael Monfils and Elina Svitolina in the quarter-finals.

The US Open mixed doubles was revamped last year to include singles stars in a bid to attract greater attention to the format.

A shorter scoring system was introduced, with only four games required to win a set in matches before the final, no “advantage” scoring, and 10-point match tie-breaks instead of a third set throughout.

In qualifying for the women’s singles, British trio Fran Jones, Katie Swan and Harriet Dart each progressed to the second round.

Jones defeated Italy’s Nuria Brancaccio 6-3 6-4 after Dart overcame 16-year-old American Jordyn Hazelitt 6-0 6-7 (1) 6-1. Swan beat another American, Katrina Scott, 6-3 6-1.

Jodie Burrage lost 7-6 (1) 6-4 to Spain’s Guiomar Maristany, while compatriot Henry Searle exited men’s qualifying following a 6-1 6-2 defeat to 16-year-old American Michael Antonius.