Defending champion Carlos Alcaraz said he always believed Novak Djokovic would escape from his two-set deficit at the US Open as the pair remained on a collision course on Saturday.Djokovic came from two sets down to beat Serbian compatriot Laslo Djere on Friday to avoid his earliest exit in New York since he lost in the third round as a teenager in 2006.

Alcaraz, who joined Djokovic in the last 16 on Saturday, went to bed before the conclusion of his rival's late night match but insisted he'd had no doubt how it would finish.

"Well, I watched the first two sets, then I had to go to sleep," revealed Alcaraz.

"But, you know, when I go to bed, I was thinking Novak is going to come back, that's for sure. He shows once again that he's one of the best in history."

It marked the eighth time Djokovic had recovered from an 0-2 hole to win a Grand Slam match, and the 38th five-set victory of his career.

"It's something crazy," said Alcaraz, who will surrender the No 1 ranking to Djokovic after the US Open.

"Stay 36 years old and doing the same things that when he was 20, it's incredible. We have to give credit about that, and it's something I admire."

Alcaraz himself certainly has his growing legion of admirers, turning in another eye-catching display in a four-set win over Evans, who gave the Spaniard his first real challenge of the week.

The world No 1 crashed 61 winners past the 26th-seeded Briton to prevail 6-2, 6-3, 4-6, 6-3 and line up a meeting with Italy's Matteo Arnaldi.

"I'm really, really happy to get through," said Alcaraz, now unbeaten in three matches with Evans.

"He's a tricky opponent. I think when we play each other it's a show on the court. We made great points, great shots, a lot of different kinds of situations.

"We play to entertain, to make the match fun... and we feel the energy (of people) enjoying that."

FEDERER FEAT INSPIRES ALCARAZ

The Spanish star broke twice to start the match and looked on course for a routine victory when he retrieved an early break in the second set to sweep into a 2-0 lead on Arthur Ashe Stadium.

But Evans countered Alcaraz's brutal groundstrokes with some crafty shotmaking of his own to extend the encounter into a fourth set.

Alcaraz produced an outrageous forehand passing shot down the line to break for 4-2, leaving Evans in disbelief as his brave resistance finally came to an end after a thrilling 3hr 11min duel.

The 20-year-old Alcaraz is aiming to become the first man to defend the US Open crown since 2008, when Roger Federer hoisted the trophy for a fifth consecutive year.

"Obviously defending the title is a goal for me. I'm looking for that. Nobody's done it here since Roger so I'd love to be part of tournament history with him."

Awaiting Alcaraz next is the 61st-ranked Arnaldi, who upset British 16th seed Cameron Norrie in straight sets.

The 22-year-old Arnaldi had never played in the main draw of a Grand Slam before this season, with a brief run to the second round at Roland Garros his best performance at a major.

He's now set to face tennis' new golden boy on the biggest stage of them all, likely in front of 23 000 spectators on the main Arthur Ashe show court.

"When I saw the draw, that was my goal, to go and play against him," said Arnaldi.

"But, you know, I never played against a World No 1. It's just something crazy to think what I was at the start of the year and where I am now.

"I'm just trying to think match after match and to enjoy this moment."