AFP

Novak Djokovic charged into his 13th US Open semi-final on Tuesday with a straight-sets win over Taylor Fritz, while home favourite Coco Gauff stayed on track for her first Grand Slam title.

Djokovic shrugged off ninth seed Fritz 6-1, 6-4, 6-4 to extend his dominance of American players in New York and take another step closer to a record-extending 24th men's Grand Slam title.

The 36-year-old Serbian star will appear in a record 47th major semi-final, eclipsing the mark he shared with longtime nemesis Roger Federer.

Djokovic awaits either 10th seed Frances Tiafoe or the up-and-coming Ben Shelton, who face off in an all-American affair in Tuesday's night session.

"I have played this sport for many years, so many epic matches and I cannot wait for another one in a few days' time," said Djokovic.

"It is a huge opportunity every time I step out on the court at this stage of my life. I don't know how many more opportunities I will get so I am trying to enjoy it as much as I can."

The three-time US Open champion defeated Fritz for the eighth time in a row, Djokovic barely allowing his error-riddled opponent to lay a glove on him.

Fritz had lost serve just once across four three-set wins in reaching his first US Open quarter-final, but the 25-year-old was broken three straight times to start the match.

Djokovic resisted four break points at 2-1 in the second set and hauled himself over the line after a rollercoaster final few games in the third set, maintaining his quest for a triumphant return to world number one next week.

Gauff swept into the last four earlier on Tuesday with a 6-0, 6-2 win over Latvia's Jelena Ostapenko in 68 minutes in the baking midday heat on Arthur Ashe Stadium.

The American sixth seed will meet the winner between this year's French Open runner-up Karolina Muchova and Romanian veteran Sorana Cirstea for a place in Saturday's final.

"It feels great, I'm so happy," said Gauff. "Last year I lost in the quarter-finals stage and wanted to do better this year. I have a long way to go but I'm happy and will be ready for the next one."

"I didn't feel comfortable at all the whole match, even at match point. She has the ability to come back no matter the scoreline so I was just trying to play every ball and hit it deep."

The 19-year-old Gauff has now won 16 of 17 matches since her first round loss at Wimbledon, picking up titles in Washington and Cincinnati to establish herself as one US Open favourites.

"There's still a lot of tennis left to play, and it's a long match and a long tournament," said Gauff.

"You know, even though the semi-finals, by theory, if you want to win there's two matches left. You can't think like that."

An out-of-sorts Ostapenko criticised the tournament scheduling as she returned to court barely 36 hours after bundling out world number one Iga Swiatek in the last 16.

"Today was not really good match from me," Ostapenko said. "I think it's really hard to recover from those night matches, because after beating world No. 1, I went to sleep at, like, 5:00 in the morning."

Ostapenko said tournament officials had led her to believe she would be given a later start on Tuesday following her win over Swiatek, which wrapped up just minutes before midnight on Sunday.

"I was pretty sure I'm gonna play at night session, because that's what they told me," she said.

"When I saw the schedule I was a little bit surprised, not in a really good way."