Thailand's Paradorn Srichaphan became the first seeded casualty in the $2.45 million Hamburg Masters on Monday but struggling Tim Henman battled into the second round.

Paradorn, the seventh seed, lost 6-4, 6-3 to Spaniard Feliciano Lopez in the claycourt event, the fifth of nine Masters Series tournaments and a warm-up to the French Open, starting on May 26.

The Thai, currently world number 10, was also an opening round loser in last week's Rome Masters, falling to Finn Jarkko Nieminen. Nieminen won again on Monday, defeating Austrian Stefan Koubek 6-4, 0-6, 6-1.

Henman, another first round casualty in Rome and struggling with a shoulder injury, managed a 7-5, 6-4 victory over American Jan-Michael Gambill.

In other early action, Spanish claycourt specialist David Sanchez defeated American Mardy Fish 5-7, 6-4, 6-2, while South Africa's Wayne Ferreira eased past German wild card entrant Alexander Waske 6-3, 6-2.

Argentina's Guillermo Coria, the 12th seed, and Spaniard Tommy Robredo, seeded 14, enjoyed comfortable victories. Coria pushed aside American Vincent Spadea 6-2, 6-2 while Robredo beat Czech Radek Stepanek 6-4, 6-3.