Jamie Murray has challenged brother Andy to prove he can be a consistently dangerous player on clay when he faces 19th seed Nicolas Almagro in the French Open third round here today.

The elder Murray brother, beaten with Max Miryni in the doubles yesterday, watched the British No1 demolish Argentina's Jose Acasuso in straight sets to earn this difficult assignment against Almagro, one of the best clay courters around.

Jamie, who will be at courtside to support his brother again today, said: "Andy should play like that more often, because it's much more effective and he would be tough to beat against anybody if he did.

"The win over Acasuso was probably Andy's best match for a year - since he hurt his wrist in Hamburg - and it was great to see him produce that kind of tennis."

Murray junior, the 10th seed, will have to be even better to emerge victorious against the Spanish baseliner who is worrying Alex Corretja, the clay court expert who is helping prepare Murray at this Slam.

Corretja, a double French Open finalist said: "You would have to put Rafael Nadal, Roger Federer and Novak Djokovic as the top three players at Roland Garros but then, after them, it probably is Almagro which is why I don't like him.

"He is a great clay-court player, has won two titles this year and possesses the best kick serve in the game.

"That serves takes you out of your comfort zone in terms of where you are hitting the shot, and Andy must also be wary of Almagro's backhand which is also a serious weapon.

"Whatever happens, Andy has made important strides on clay. That's important and, after the way he played against Acasuso, who knows what he could do against Almagro.

"But, as I have said, this is an outstanding guy on clay and definitely in the top five of players on this surface up there with David Nalbandian, David Ferrer and Carlos Moya." Almagro is reported to have a wrist problem that affects his backhand and was recently told to toughen up by Spanish Davis Cup captain Emilio Sanchez if he wants to make the most of his talent.

Meanwhile, Roger Federer has turned to Greg Rusedski's former coach to help his bid for a first French Open title.

The world No1 split with Australian Tony Roche last year and is now using Sven Groeneveld in an attempt to complete his collection of all the Slam titles.

The Swiss, who earned a third-round clash with Mario Ancic by beating Spain's Albert Montanes 6-7, 6-1, 6-0, 6-4, said: "I have known Sven for quite a long time. He was still playing in the national centre when I was 14, so I've known him since then.

"Then he also did a pretty good job during the Davis Cup for us. So when I was left without a coach, I thought I would organise a few things with him.

"He can be good fun and we can have good laughs, but he can also be very serious and we can work very hard together. So he's great. I'm very happy with what he does and he analyses my game."

Fourth seed Nikolay Davydenko easily defeated fellow Russian Marat Safin 7-6, 6-2, 6-2 to set up a third-round match against Croatian 28th seed Ivan Ljubicic. Defending champion Rafael Nadal beat France's Nicolas Devilder 6-4, 6-0, 6-1.

Russian Anna Chakvetadze became the biggest casualty in the women's draw, losing 6-4, 7-6 to Estonian Kaia Kanepi in the second round.

Sixth seed Chakvetadze, a quarter-finalist at Roland Garros last year, dropped serve four times and bowed out after 99 minutes when she lost the tie break 7-2.

Fourth seed Svetlana Kuznetsova had no problems defeating American Vania King 6-4, 6-2 to reach the third round, while top seed Maria Sharapova was leading 6-2, 2-3 when she successfully called for an end to her match with Bethanie Mattek due to bad light.

That match will be completed today on the Phillipe Chatrier court after second seed Serb Ana Ivanovic, has played the No30 seed from Denmark Caroline Wozniacki.