Djokovic's 6-3, 7-5, 3-6, 6-4 victory over the last American left in the men's draw sent him into a record-equalling 14th US Open semi-final.

He will now have two precious days of recovery time to prepare for a highly-anticipated tussle with the red-hot Alcaraz on Friday.

"It's not going to get easier. I tell you that," said Djokovic.

"The next couple of days is really key for me to really get my body in shape and ready to battle five sets if it's needed.

"I just would really love that. Would love to be fit enough to play and to play, you know, potentially five sets with Carlos. I know that my best tennis is going to be required, but I'd rise to the occasion."

Djokovic and Alcaraz will square off for the first time since the Australian Open quarter-finals in January when the Serbian won in four sets to take a 5-3 edge in their rivalry.