Caroline Wozniacki says her hard work is paying off as the world number 11 prepares to face unseeded Peng Shuai in the US Open semi-final on Friday.

The Dane overcame a tricky opening game to beat 13th seed Sara Errani 6-0, 6-1 and set up a meeting with China’s Peng – who has not dropped a set at the tournament.

Wozniacki, 1.32 to make the final, is back to her best with a renewed sense of purpose after putting her all into tennis again following the much-publicised breakup of her relationship with golfer Rory McIlroy earlier this year.

“It’s been a pretty up and down year for me,” she said. “To be here in the semi-finals of the US Open once again is an incredible feeling. Definitely, hard work pays off. I’m here and I’m so happy.”

The match began badly for Wozniacki, who struggled with the warm winds that blew through Arthur Ashe Stadium. She hit an ugly double fault on her second serve of the opening game and had to fend off four break points to hold serve.

But the tenth seed then broke her opponent three times to take the first set without dropping a game and was equally dominant in the second as she bashed 26 winners to the Italian’s 12.

Wozniacki has reached the last four of a Grand Slam tournament for the first time since the 2011 US Open – a three-year drought that happens to correspond almost exactly to the length of her relationship with McIlroy.

The 24-year-old Dane has thrown herself back into the sport that once saw her rise to No. 1 in the world. She won a tournament in Istanbul the same day McIlroy claimed the British Open and has kept on rolling, playing arguably the best tennis of her career.

Her next opponent Peng Shuai was equally impressive in routing Swiss teenager Belinda Bencic in the lower half of the women’s draw where the leading seeds have vanished in upsets.

The 28-year-old from Tianjin has been impeccable on serve throughout the five rounds where she has lost only three of 17 break points faced and never lost more than four games in a set.

The Chinese, available to back at 3.50 on the Money Line, has won only one set against Wozniacki in their past five meetings, but the resurgent former world number one is aware of the threat to her potentially setting up a meeting with her friend Serena williams in the final.

“She’s been playing well. She’s playing aggressively,” Wozniacki said of Peng. “She’s strong from both sides. She’s been serving well. It’s going to be a difficult match. But it’s going to fun.”