Murray and fellow Briton Neal Skupski came from behind to beat Americans Jack Sock and Jackson Withrow 4-6 6-1 7-6 (7-4) in their men's quarter-final.

The Scot, 33, returned a few hours later with American Bethanie Mattek-Sands to beat Samantha Stosur and Rajeev Ram 6-3 6-1 in the mixed.

"We were on fire," said Murray, who won the 2018 title with Mattek-Sands.

"We didn't give them a chance, I'm really happy to be in the final again."

'I'm going to sleep - it's been a long day' - Murray

Murray and Skupski, who only teamed up in the spring, battled back from a break down in the third set to beat Sock and Withrow on Louis Armstrong Stadium.

At 4-3 up in the first set, the Britons missed two break points that would have allowed them to serve for the set and were immediately punished as the Americans broke in the very next game.

The Britons responded emphatically, though, breaking serve twice and conceding just one game in a dominant second-set showing.

The momentum swung once more in the third as the US pair raced into a 4-1 advantage, but Murray and Skupski levelled at 5-5 before closing out the decisive tie-break with three unanswered points.

The 15th seeds, who have now won nine of their past 11 matches, will face top seeds Juan Sebastian Cabal and Robert Farah for a place in the final after the Colombians beat Britain's Luke Bambridge and Japanese partner Ben McLachlan 6-4 6-4.

The US Open is only Murray and Skupski's second Grand Slam outing as a doubles pairing, having exited Wimbledon in the first round in July.

Murray has lifted a doubles title every year at Flushing Meadows since 2016.

He won the men's doubles with Bruno Soares in 2016 and the mixed doubles in 2017 with Martina Hingis and in 2018 with Mattek-Sands.

He is now within touching distance of another after a comfortable mixed doubles win over third seeds Stosur and Ram, where they won 10 of the final 11 games to underline their dominance.

They will face the top seeds of Taiwanese Chan Hao-ching and New Zealander Michael Venus or fourth seeds Latisha Chan and Ivan Dodig in Saturday's final.

But before that, Murray has one thing he needs to do.

"I'm going to sleep, it's been a long day for me," he smiled.