Paradorn Srichaphan has a tough first round appointment in the US Open while compatriots Tamarine Tanasugarn and Danai Udomchoke were knocked out in the first round of the qualifying event on Wednesday.

Paradorn, who suffered a wrist injury during his defeat to Nikolay Davydenko 6-4 6-1 in New Heaven on Wednesday, will play Argentine rising star Jose Acasuso, who is one of the most improved players on the ATP tour this year.

Despite his unbeatable 2-0 record against the 24th-seeded Acasuso, winning 6-4 7-6 (7-5) in Miami in 2003 and 7-5 6-4 6-4 in the 2004 Australian Open 2004, it won't be a walk in the park for the Thai this time. Since crashing out in the first round at Wimbledon, Paradorn has reached only one quarter-final in Indianapolis. Not to mention the wrist injury which has troubled him for several weeks.

The world No 27 Acasuso, on the contrary, has had a very successful season where he has rocketed to a career high rank of 20 last month. He won in Chile and reached the final in Stuttgart, but his most impressive results were a semi-final in the Hamburg Master Series and a quarter-final in the Toronto Master Series.

In the qualifying competition held on Wednesday night, Tamarine and Danai, both seeded, fell flat in their attempts to make the main draw of the year's final Slam.

The ninth-seeded Tamarine made a plethora of unforced errors as she went down easily to Russian Alisa Kleybanova 6-3 6-1.

"I played very bad. I tried too much and it ended like that. It's just I want to get back to the top 100 as soon as possible," said Tamarine, who is now No 118 in the world.

Seeded 13th, Danai also failed to live up to his billing as he fell to American big-server Jeff Morrison 6-3 6-3.

Roger Federer will open the defence of his US Open crown by taking on Wang Yeu-Tzuoo of Taiwan.

The world No 1 will be bidding to become only the third player in the professional era to win three straight titles at Flushing Meadows. The others were John McEnroe (1979-81) and Ivan Lendl (1985-87).

The Swiss star has never before played the 21-year-old Wang, who is ranked 109th in the world, and he looks set for a comfortable run into the second round.

Wednesday's draw was less kind on his top rival and second seed Rafael Nadal. The 20-year-old Spaniard was pitted against former finalist Mark Philippoussis.

The Australian had to accept a wildcard into the event after slumping down the rankings due to injury, but on his day and fully fit he can still be a match for the best.

Andre Agassi, in his farewell tournament, opens against Romanian veteran Andrei Pavel of Romania, but up-and-coming Marcos Baghdatis of Cyprus would prove a tough hurdle for the 36-year-old former winner to pass in the second.

Fourth-seeded David Nalbandian of Argentina will take on German newcomer Michael Berrer, while third seeded Croat Ivan Ljubicic will get underway with a tough tie against Spanish serve and volleyer Feliciano Lopez.

Federer looks to have a reasonably comfortable run into the last eight where he could meet top-ranked American and fifth seed James Blake who enjoys playing in front of his hometown crowd.

If the seedings are confirmed, Federer would meet Nalbandian in a repeat of last year's semi-finals while Nadal, who has yet to get beyond the third round in New York, would take on Ljubicic.

The men's draw also turned up an intriguing first round clash between fading British veterans Tim Henman and Greg Rusedski. The winner would likely take on Federer in the second round.

Young compatriot Andy Murray, who is seeded 17th, will be facing a qualifier.

 In the women's event top seed Amelie Mauresmo of France starts against a yet-to-be-decided qualifier, but could face early on old nemesis Serena Williams who is unseeded after a long stay on the sidelines due to injury.

The younger of the Williams sisters must first defeat Spain's Lourdes Dominiguez Lino.

Second-seed Justine Henin-Hardenne of Belgium, who lost to Mauresmo in the Wimbledon final, is in the bottom half of the draw going up against Italy's Maria Elena Camerin.

Third seed Maria Sharapova takes on Michaella Krajicek of the Netherlands, the sister of former Wimbledon winner Richard, while fourth seeded Russian Elena Dementieva, a semi-finalist last year, opens against Laura Granville of the United States.

The semi-finals potentially are Mauresmo against Sharapova and Henin-Hardenne against Deme ntieva.

Last year's winner Kim Clijsters of Belgium will not defend her crown having pulled out due to an injury to her left wrist.