Defending champ Swiatek upset by Ostapenko at US Open as Djokovic cruises

Defending champion Iga Swiatek crashed out of the US Open on Sunday after defeat by Jelena Ostapenko and will lose her number one ranking, while Novak Djokovic marched into the quarter-finals.

Swiatek grabbed the opening set against Ostapenko but the unpredictable Latvian stormed back to win 3-6, 6-3, 6-1 and secure her fourth victory in as many meetings with the Polish star.

The mercurial Ostapenko, who had never made it to the last 16 in New York before this week, goes on to face title contender and home favourite Coco Gauff in the last eight after blasting Swiatek out of the tournament.

Undeterred by falling behind, Ostapenko's typically fearless and aggressive approach rendered Swiatek helpless and ensures there will be a new world number one after the US Open.

Swiatek's 75-week reign will come to and, with rival Aryna Sabalenka set to take over top spot.

"I always expect a tough battle against Iga, she's such a great player and won many Slams and is so consistent," said Ostapenko, the 20th seed and 2017 French Open champion.

"I knew I had to be aggressive and play my game because that's what she doesn't like.

"I was just thinking that I have to play until the very last point, until we shake hands. I felt like I was playing better and didn't give her many chances."

Gauff ended Caroline Wozniacki's fairy tale Grand Slam comeback earlier Sunday as the sixth seed saw off the former world number one 6-3, 3-6, 6-1.

The 19-year-old registered her 15th win in 16 matches, a run including titles in Washington and Cincinnati last month.

Gauff sparked into life after dropping the opening two games to pocket the opening set, but Wozniacki - playing her first Grand Slam in over three years - wound back the clock to level the match.

Two-tim