NEW YORK — Novak Djokovic’s strange US Open took another bizarre turn as he advanced to the semifinals on Tuesday when Frenchman Jo-Wilfried Tsonga retired at the start of the third set, trailing 6-3 6-2.

In the women’s contest, former world No 1 Caroline Wozniacki reached the semifinals of on Tuesday with a ruthless 6-0 6-2 win over wounded Latvian Anastasija Sevastova.

Tsonga took a medical timeout during the changeover at 5-2 of the second set and had the area below his left knee taped.

World No 1 Djokovic held serve to love to close out the set and the Frenchman walked off, giving the Serbian passage into the last four for a 10th consecutive time.

It has been an unusual tournament for Djokovic who has played only two full matches. He was given a walkover in the second round and a retirement after six games in the third before Tsonga.

“I’m in the semifinals, so that’s what matters for me the most,” Djokovic told reporters after 83 minutes in Arthur Ashe Stadium.

“I know Jo for a long time, we grew up playing in the junior circuit as well. He’s a fighter, he’s somebody who loves the big stage. This is something I’m sure he didn’t wish for.”

The first five games progressed on serve to offer promise of a big-hitting battle.

But Tsonga wobbled in the sixth game, committing three double faults to lose serve, the first of three successive breaks that left the Serb with a 5-3 lead.

From that point, Djokovic dominated.

Tsonga said when he felt pain in his knee, he knew it was over. “It’s something I had already in the past,” he said.

“When I have my knee, of course, it’s already tough to play against one of the best tennis players.

“But when I don’t have my knee, I have no chance to come back from two sets to love.”

Australian and French Open champion Djokovic came to New York with question marks, having lost in the third round at Wimbledon and the first at the Rio Olympics while battling a nagging left wrist injury.

He was unfazed by his sparse time on court.

“In this stage of the season, considering some physical issues I have had … this was the scenario that I needed and I wished for,” he said.

“I got a lot of days off and recovered my body. Right now I’m feeling very close to the peak.”

Djokovic will play for a place in the title decider against another Frenchman in 10th seed Gael Monfils, who beat compatriot Lucas Pouille in straight sets.

Monfils has yet to beat Djokovic in 12 career meetings.

Sevastova injured

Sevastova, the first Latvian to reach a Grand Slam quarterfinal, saw her US Open hopes come to a painful end when she rolled her ankle chasing down a ball on Wozniacki’s opening serve.

“For sure it was affecting my play but I’m not a person that likes to retire during a match, so I just tried my best,” said the 48th ranked Sevastova, who fought bravely to the finish.

“It’s tough to end like that, but it’s tennis. I could have played amazing but still lost. It would hurt more, I think.”

After watching Sevastova crash to the court and then get up, Wozniacki said she had taken no chances with a spot in the semifinals on the line.

With her opponent hobbled, the Dane showed no mercy as she moved in for the kill, keeping Sevastova running from sideline to sideline.

“I’ve rolled my ankle several times so I feel real sorry for her,” said Wozniacki, twice a US Open finalist. “But I was just extra focused.

“She stood up and I knew if she can still walk and still put weight on it and stuff then she’s going to go obviously more for her shots and stuff like that.

“I kept serving well and made her run.”

While there was no room for sympathy on Arthur Ashe Stadium court, Wozniacki knows the damage a bad ankle can cause having been sidelined herself for three months this season.

The 26-year-old was forced to withdraw from the French Open due to a sore ankle and then had a first round exit at Wimbledon, sinking her world ranking to 74 by the time she arrived at Flushing Meadows.

But for Wozniacki, ranking like age, is just a number.

“Being 70-something doesn’t really mean much to me,” shrugged the Dane, who next meets second seed Angelique Kerber, a 7-5 6-0 winner over Roberta Vinci.

“I still believe and feel like I’m one of the top players and grinding my way back, so that’s why I’m saying for me right now the ranking is just a number.

“There is a long way for me right now to get back to No 1 but I’m doing my best to just play my best tennis and have fun with it.

“It’s really all that I can do right now.”

Reuters