Jamie Murray, Britain's first Wimbledon winner for 20 years, will today start a frantic search for a new mixed doubles partner after discovering Jelena Jankovic cannot help defend the title they won last year.

Murray and Jankovic were the feelgood story from last year's Championships and their defence would have been one of the highlights of the 2008 tournament.

However, Jankovic has a lingering arm problem that means she will only play in the women's singles, leaving Jamie to try to put together a combination that could mount a serious challenge for the mixed doubles title.

Jamie, elder brother of British No1 Andy, claims he has "two or three" possible alternatives to Jankovic, the Serbian world No3 who reached the French Open semi-finals despite soreness in her right forearm.

Murray said: "Jelena's having problems, which is why she didn't play in Edgbaston this week. She will just concentrate on the singles at Wimbledon. It would have been good to defend the title but it's not the end of the world.

"When she told me, I didn't have that feeling of shock as I half-expected it. I am still looking to play in the mixed, although I haven't yet got a partner."

When Jankovic and Murray beat Jonas Bjorkman and Alicia Molik last summer it was the first British success at Wimbledon since Jeremy Bates and Jo Durie clinched the same title in 1987.

Meanwhile, Ernests Gulbis (right), the Latvian world No51, is promising to be "pumped" and ready to inflict a shock defeat on Andy Murray when they meet in today's third round match at Queen's.

Like 11th- ranked Murray, Gulbis carries his nation's tennis hopes on his shoulders and, while only 19, his surge into the French Open quarter-finals last week proved he has genuine talent. Gulbis defeated Tim Henman at the French Open last year - his Grand Slam debut - and has recorded wins over top-10 players Tommy Robredo and James Blake.

He beat Italy's Andreas Seppi in three sets in the second round at Queen's and said: "We are going to play on Centre Court, so I will be pumped against Andy.

"I am still adjusting my game for grass courts but I think with every match I will play better and better.

"I beat Robredo when he was top 10, now Blake in Paris, and that gives me a lot more confidence. I know that I can play at the same level as the top players.

"My first match on grass was here last year. We don't have any grass courts in Latvia because it's very tough to keep them in good shape. No chance.

"When I played against Henman he was going down and not the player who made the Wimbledon semis. I have never played against Murray or practised with him."

Top seed Rafael Nadal, the four-time French Open champion, will be aiming to follow his 6-2, 6-2 victory over Bjorkman with another clinical performance against Japan's Kei Nishikori. The 22-year-old, who won again in Paris last week, is desperate to prove he can win a Grand Slam away from clay.

He has reached the last two Wimbledon finals and said: "Wimbledon is very important and I want to improve on every surface.

"I am still young and I have four Grand Slams already. I want to have more, if it's possible, and one on a different surface."

Second seed Novak Djokovic, the Australian Open champion, reached the third round with a 6-2, 7-6 win over Croatia's Roko Karanusic.