ANDY MURRAY approaches his third-round match with a sense of wariness after an astonishing week of upsets and withdrawal at Wimbledon.

The Scot will play Tommy Robredo of Spain today and will not walk out on to the Centre Court with any over-confidence in a week that has witnessed the men's draw losing such as Roger Federer, Rafael Nadal, Jo-Wilfried Tsonga, Marin Cilic and Milos Raonic.

"[Steve] Darcis beat Rafa, Roger has just lost to [Sergiy] Stakhovsky, Tsonga lost to [Ernests] Gulbis. Who's to say I can't lose to Robredo?" asked Murray. "These things happen all the time in sport. I just think [because of] the consistency of the top players for the last eight, 10 years, people are so shocked. I think this used to happen a lot more, but I don't worry about those things. I know if I don't play well, I'll lose. That's why I'll be ready for that match and not worry about anything else."

Murray's determination was lightened with his response to a Twitter challenge from a fan asking him to play Serena Williams. "I'd be up for it, why not?" said Murray whose challenge was met with a jovial "let's get it on" from Williams, who moved smoothly into the third round yesterday with a crushing 6-3,6-2 defeat of Caroline Garcia of France.

Murray said of the 16-time grand slam winner. "I've never hit with her but she's an incredible player and I think people would be interested to see how the styles match up. It's happened in the past with Jimmy Connors and Martina Navratilova. How about Las Vegas as a venue?" he said.

Williams said: "I doubt I'd win a point, but that would be fun." But she later asserted she might take a game against the men's No.2.

In 1998 at the Australian Open, Serena and Venus Williams played individual sets against Karten Braasch, a German player ranked outside the world top 200. He beat Venus 6-2 and Serena 6-1. "I was really young. I'm a lot more experienced now," said Serena, who was 16 at the time.

She said of Murray: "He's probably one of the top three I definitely don't want to play. But, yeah, maybe we can have a little bit of a showdown."