Former world number one Caroline Wozniacki reached the semi-finals of the US Open with a ruthless 6-0 6-2 win over injured Latvian Anastasija Sevastova.

Sevastova, the first Latvian to reach a grand slam quarter-final, saw her hopes come to an 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.

After watching Sevastova crash to the court and then get up, Wozniacki said she had taken no chances.

While 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.”

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, sinking her world ranking to 74 by the time she arrived at Flushing Meadows.

But for Wozniacki 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.”

Quarter-final: Pliskova bt Konjuh 6-2 6-2.