Carlos Alcaraz marched into the quarter-finals of the US Open on Sunday as two-time Grand Slam champion Barbora Krejcikova staged a miraculous escape to advance to the last eight.

Spanish second seed Alcaraz, the 2022 champion, stayed on course for a semi-final showdown against Novak Djokovic after overpowering France's Arthur Rinderknech in straight sets.

The 22-year-old five-time Grand Slam champion was made to work hard in a tight first set but eventually pulled away to win 7-6 (7/3), 6-3, 6-4 on the Arthur Ashe Stadium court.

"I think my style of tennis suits pretty well the energy here in New York," said Alcaraz, who has yet to drop a set at the tournament.

"The energy is special playing the day session, playing the night session. It doesn't matter, people are always there. I love it and I think that's why I play my best tennis here," he added.

The win moves Alcaraz a step closer to a potential last four assignment with tennis icon Djokovic.

Djokovic, 38, continues his latest bid for a record 25th Grand Slam singles title later Sunday in a night match against unseeded German Jan-Lennard Struff.

Alcaraz will face Czech 20th seed Jiri Lehecka in the quarter-finals on Tuesday.

Lehecka reached the quarter-finals of a Grand Slam for only the second time after battling past veteran Frenchman Adrian Mannarino, winning 7-6 (7/4), 6-4, 2-6, 6-2.

"I'm a bit speechless because it's been a hell of a match," said Lehecka, who is poised to crack the top 20 after matching his quarter-final run at the 2023 Australian Open.

"Definitely an unbelievable week and a half for me. I've been playing well," he said.

In the women's draw, the Czech Republic's unseeded former French Open and Wimbledon champion Krejcikova conjured a remarkable escape to oust Taylor Townsend, saving an incredible eight match points before digging out a 1-6, 7-6 (15/13), 6-3 victory.

Krejcikova fought off a match point on her own serve at 5-4 down in the second set, and then somehow survived seven match points in an enthralling tie-breaker to move on.

"What a match," said Krejcikova, who revealed she had wondered if she would ever play tennis again after missing the opening months of the season with a back injury.

"I was sidelined for six months and didn't know if I would ever play again. I'm super happy I can be here."

Krejcikova will face American fourth seed Jessica Pegula in the quarter-finals.

Pegula, beaten in the final last year, advanced to the last eight after breezing past compatriot Ann Li 6-1, 6-2 on the Arthur Ashe Stadium court. (AFP)