Nikolay Davydenko does not look like a tennis player. In fact, he does not look like a professional athlete at all. He is small, skinny and has the balding pate of a much older man, but he is ranked No.4 in the world for a reason, and Andy Murray will go into today's fourth round encounter with him at the Pacific Life Open in Indian Wells knowing exactly how difficult an opponent he can be.

Murray played Davydenko in Indian Wells a year ago and, though his life and career has changed immeasurably in the intervening 12 months, he can expect much the same from the obstinate Russian, whose appearance hides a canny and devastatingly effective game.

After losing to him here and again at the US Open, Murray finally worked out how to beat Davydenko in Doha in the first week of this season to score a win which should give him some confidence as he heads warily into today's encounter.

He knows, though, that he can expect to be detained a lot longer than he was in either of his first two matches, both of which lasted little over an hour. Given that the forecast is for more hot, dry days, Murray will be glad of all the physical conditioning work he has been undertaking with his fitness trainer, Mark Grabow.

"Davydenko's strength is retrieving and, you know, he hits the ball great on the run and returns really well. So it may be a different match, and it's important for me to serve well and keep a good head out there against him.

"Every match I play against him, I've had to change tactics a little bit throughout. But I guess sometimes against him, you have to play more aggressive, because when you do give him chances to dictate, he can make you do a lot of running. And, obviously, in these conditions, it's not the best thing to be doing."

Murray was not detained unduly yesterday when he and Tim Henman teamed up again for the doubles. The two Britons combined well to beat the Chris Haggard, of South Africa, and the Dutchman Rogier Wassen 6-3, 6-0 and move through to the third round.

Great Britain's Davis Cup captain John Lloyd heartily approves of Murray and Henman's decision to get some doubles practice ahead of the team's tie against Netherlands over Easter weekend next month and he must be even more thrilled at the way they have combined in their first two matches in Indian Wells.

Henman is indisputably team leader and seems to have no qualms about bossing the usually forthright Murray around. The teenager took it like a lamb when the Englishman gave him tactical advice and instructions yesterday, largely because he so admires Henman that he would probably run naked around the Indian Wells Tennis Garden if Henman told him too.

They have a brotherly relationship and, at 32 and in his 15th year on the circuit, Henman is entitled to offer advice to the younger man, especially given the amount of support he has given Murray and his brother Jamie as they have begun their respective careers.

He is also an excellent doubles player and he and Murray brought the best out of each other on court. Both men serve and return well and have silky skills around the net, which they used to good effect, showboating for the sizeable crowd which had gathered to watch them.

Playing Davydenko is unlikely to be nearly so much fun for Murray; the potential rewards, though, will be far greater.

Defending champion and world No.1 Maria Sharapova is out of the women's tournament after losing 6-4, 5-7, 6-1 in the fourth round to fellow Russian Vera Zvonerava. Sharapova was at 5-3 and cruising in the second set before her game unravelled in embarrassing fashion and she lost eight straight games. She made 47 unforced errors and served 13 doubles faults overall and looked tetchy and out of sorts throughout. She is now certain to lose No.1 ranking to Justine Henin when the new standings are released on Monday.