Defending champion Carlos Alcaraz shrugged off a battling performance from British 26th seed Dan Evans to win in four sets and reach the last 16 of the US Open on Saturday.

Alcaraz crashed 61 winners past Evans as the world number one won 6-2, 6-3, 4-6, 6-3 to line up a meeting with Italy's Matteo Arnaldi, ranked 61st.

"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."

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."

mw/rcw