NEW YORK -- Suggest to defending champion Lleyton Hewitt that this U.S. Open is his to lose, that there are few challengers to the world's No. 1 player, and he just bristles.

"That's rubbish,'' he snapped after beginning his defense Tuesday with a routine 6-2, 6-3, 6-3 victory over Nicolas Coutelot.

So which players does Hewitt -- winner of the last Grand Slam at Wimbledon -- believe are legitimate threats to him?

"There's a lot of challengers,'' he said. "Most people know who they are.''

Then he rattled off the names of the usual suspects -- Andre Agassi and Marat Safin. Andy Roddick, too. Also Tommy Haas, Tim Henman, Greg Rusedski and Juan Carlos Ferrerro.

Safin and Roddick held up their end of the bargain Tuesday, opening with wins.

Safin won a test of survival, outlasting Nicolas Kiefer 6-3, 4-6, 4-6, 6-4, 7-6 (4) in a five-set marathon that lasted 4 hours, 31 minutes and left both players exhausted and cramped.

Roddick, seeded No. 11 and three days from his 20th birthday, needed treatment for a blister on his right hand and defeated Martin Verkerk 7-6 (2), 6-3, 6-4.

Ferrero, No. 7, won two tiebreakers before subduing Wayne Arthurs 7-6 (4), 7-6 (2), 3-6, 7-5.

Haas, Henman and Rusedski get started Wednesday. So does four-time champion Pete Sampras, the man Hewitt beat for the title last year but a name he left off the list of challengers.

"I'm forgetting guys, I know I am,'' Hewitt said. "There's a lot of guys. I think it's getting more and more open. I think it's an extremely tough field this year.''