(BSS/AFP) - Carlos Alcaraz and Novak Djokovic can set up a heavyweight clash at the US Open on Tuesday, while Aryna Sabalenka aims to take another stride towards defending her title.

Spanish second seed Alcaraz is the only man yet to concede a set at the tournament as he goes in search of a second US Open title and sixth Grand Slam.

The 22-year-old takes on Czech 20th seed Jiri Lehecka, who is in the quarter-finals of a major for only the second time.

"Against a player like Carlos you need to bring your best," said Lehecka. "He`s one of the two biggest challenges right now in tennis."

Lehecka defeated Alcaraz in Doha in their only meeting on hard courts, with the Spaniard getting the better of the Czech in another three-set tussle at Queen`s in June.

The winner of that match will face either 24-time Grand Slam champion Djokovic or Taylor Fritz, last year`s US Open runner-up and only American man left in the draw.

History undoubtedly favours Djokovic as the Serbian star has won all 10 past meetings, but he will be on his guard against Fritz.

"Taylor definitely is one of the guys that no doubt has a game, has a potential to be a Grand Slam winner," said Djokovic.

"He was playing finals here last year, so he was one match away, so there is no reason not to believe that he can make it. Hopefully not this year, but any other year is fine."

Djokovic is coming off his best performance of the fortnight against Jan-Lennard Struff but has shown signs wear and tear -- an issue which has plagued the 38-year-old at Grand Slams of late.

"Hopefully the crowd is really going to get behind me now because I am the last (American) guy," said Fritz, the fourth seed.

- Sabalenka under pressure -

No woman has retained the title in New York since Serena Williams won three in a row from 2012 to 2014, but Sabalenka is revelling in the pressure of being the world`s top-ranked player.

"I think pressure is part of our lives, and I think pressure is normal," said Sabalenka.

"I`m enjoying being world number one. I`m enjoying this pressure. I`m working really hard to be where I am.

"For me, it`s a fun life if you`re really enjoying your job."

The top seed takes on former Wimbledon champion Marketa Vondrousova to kick off the night session in Arthur Ashe Stadium.

Jessica Pegula, who lost to Sabalenka in last year`s final, is first up on Tuesday against two-time major winner Barbora Krejcikova.

Pegula said a night out with friends at an escape room helped her bring a relaxed approach into the US Open following a rotten run of form.

"I felt terrible coming into this tournament, honestly," said Pegula.

"Went and did an escape room with my friends and had, like, two drinks and was, like, I need to just chill and stop getting so frustrated and overthinking all these practices."

Krejcikova pulled off one of the great escape acts by saving eight match points against Taylor Townsend in the last 16.

The Czech had wondered if she would ever play tennis again after missing the opening months of the season with a back injury.

"Just four months ago I was off the court, I couldn`t play, I couldn`t practice, I didn`t know if I will ever be back," said Krejcikova.