Britain's Tim Henman slumped to a dismal first-round defeat at the U.S. Open on Tuesday, beaten 6-4, 6-2, 6-2 by Spain's Fernando Verdasco.

The 12th seed, a semi-finalist last year, looked sluggish and error-prone on Louis Armstrong Court and the loss means he is likely to tumble down the men's rankings.

Henman has been suffering from a back problem and Verdasco, ranked 48, swept through the first two sets before the Briton lost his temper in the third set.

The 30-year-old was furious that the umpire failed to over-rule a Verdasco forehand that looked long. He immediately lost serve to trail 2-1 and subsided meekly after that.

Fellow Britons Greg Rusedski [Images] and Andy Murray also play their first round matches on Tuesday.

However, champion Roger Federer [Images] had things his way, hammering out a warning to his rivals for the U.S. Open title. He beat Czech Ivo Minar 6-1, 6-1, 6-1 to reach the second round.

The world number one and top seed needed just over an hour to clinch victory and set up a meeting with either Frenchman Fabrice Santoro or Juergen Melzer of Austria.

Minar, the world number 77, was given no chance to settle on his first U.S. Open appearance. Federer rattled through the first two sets in 36 minutes.

The Czech put up a little more resistance in the third set until the fourth game when he dropped his serve and the champion romped to victory.