Tim Henman insists he was not shocked by his Australian Open first-round defeat by Dmitry Tursunov as he continues to recover from an injury-disrupted 2005.

After falling behind in the opening set Henman recovered to take the lead, but Tursunov dominated the second and third sets to open up a match-winning advantage and then recovered from 1-5 down in the fourth set to win 5-7 6-3 6-4 7-5.

Having never been beyond the fourth round in nine previous visits to Melbourne Park, 31-year-old Henman continued a miserable recent run at the Grand Slams that saw him get no further than the round of 32 at any of last year's four big tournaments.

Beaten in the first round of the Australian Open two years ago, Tursunov will now play Spanish 16th seed Tommy Robredo as he looks to eclipse his best finish in a major, his fourth-round appearance at Wimbledon last summer - when he also beat Henman in the second round.

While he was obviously disappointed with the result, having had his chances throughout the match, Henman was not distraught after the defeat.

''I know where I'm at right now. I've got to regain some momentum in my game,'' Henman said.

''With the limited sort of schedule I played at the latter part of last year, and obviously starting afresh this year, the priority is to be out there healthy and competing.

''Don't get me wrong, it is disappointing to lose, and certainly when I should have been in a fifth set, that is frustrating.

"But I tend at this stage not to dwell on probably the last 15, 20 minutes.

''For the majority of the match, it was incredibly close. As I said, there were some pretty good aspects to my game. But you can't afford to let a lead slip like that in a set.''

Tursunov made the brighter start to the match to lead with a break but he was unable to capitalise on the opportunity as the more experienced Henman fought back to take out the set.

But just when it appeared Henman had steadied and was ready to go on to assert his authority it was instead Tursunov who made the running and quickly levelled the match before then moving ahead.

Henman lifted significantly in the fourth set and raced to a 5-1 lead as the Margaret Court Arena crowd anticipated a five-set thriller, but Henman was unable to close out the match in the eighth or tenth games.

And having twice survived as Henman served to keep the contest alive, Tursunov put his nose in front for the first time in the set when he held serve in the 11th game, and then sealed his triumph when he put away a cross-court forehand as Henman came to the net.

Andy Roddick had no trouble seeing off the challenge of Swiss qualifier Michael Lammer, winning 6-4 6-2 6-2.

Argentina's David Nalbandian survived a major scare to down Thai qualifier Danai Udomchoke 6-2 6-2 1-6 6-7 (4-7) 6-1 in his first-round match.

Nalbandian's compatriot Gaston Gaudio earlier breezed into the second round after Romanian Razvan Sabau retired while trailing 6-2 5-0 against the clay court specialist.

American Robby Ginepri signalled his title aspirations with an easy 6-1 6-4 6-2 victory over Austrian opponent Jurgen Melzer.

Radek Stepanek of the Czech Republic also had little trouble dispatching Swede Bjorn Rehnquist 6-1 6-2 6-2, while world number 14 David Ferrer had a tougher ask in his clash with Frenchman Florent Serra, the Spaniard dropping the first set before edging his way to victory 4-6 6-3 6-1 6-4.

Jarkko Nieminen of Finland, who won the Heineken Open in Auckland last week, continued his stellar form with a 6-2 6-3 6-1 victory over Australian Marc Kimmich.

Meanwhile, Croatian Davis Cup hero Mario Ancic advanced with a relatively comfortable 6-4 4-6 6-3 6-4 win over Argentinian Agustin Calleri.

American Taylor Dent could not win a tie-breaker as he folded in his clash with Spaniard Guillermo Garcia-Lopez, crumbling 7-6 (7-4) 6-3 7-6 (7-4) in a tight match.