Serena Williams and Caroline Woz­niacki will put their friendship aside today to do battle for the US Open title.

Williams and Wozniacki have one of the closest friendships on tour but, as the world No1 pointed out, she is well used to having to cope with personal feelings on court.

“If I can play Venus, I can play anybody,” Serena said of her sister.

Williams and Wozniacki have be­come even closer during this sum­mer, spending what appeared from the many pictures to be a riotous week together in Miami in May.

Both had gone out of the French Open early while Wozniacki was getting over the shock ending to her engagement to Rory McIlroy. “Serena is a fun girl,” said Wozni­acki. “She’s so nice to hang out with. Always makes me laugh.

“But I’m pretty good at separat­ing things on the court and off the court. It’s definitely going to be a huge match on Sunday. The friend­ship, while we are on court, is put aside. We are both competitors. We will just be fighting for every point.”

While it is no surprise to see Wil­liams in the final for the third year running, Wozniacki’s resurgence has been more unexpected.

The Dane was a prodigious tal­ent, a US Open finalist at 19 and world No1 by 20. But over the last three years, success on the biggest stage has dried up.

“I have definitely learned a lot in those years,” she said. “I have had more matches under my belt. I have learned more about myself.”

The Dane has only won one of her previous nine matches against Wil­liams but has recently pushed her close twice in Montreal and Cincin­nati.

“When she’s on fire, she’s hard to beat,” Wozniacki said. “But I have had two tough matches against her the last few weeks. I was really close. Hopefully for me, third time’s the charm.”