Tommy Haas goes through the second round

Defending champion and top seed Tommy Haas was given a tough test by qualifier Ramon Delgado in the second round of the TD Waterhouse Cup on Wednesday but emerged with a 1-6 7-6 6-4 victory.

The German rallied from a first set loss to overcome his Paraguayan opponent but was plagued by a sore shoulder throughout in the final warm-up event for next week's U.S. Open.

"The shoulder is like a roller-coaster at the moment -- up and down," he said.

"At one point in the second set I thought I may have to default, but I hung in there. I was very close to calling a trainer to have my arm massaged.

"It's a pain having to worry about the shoulder rather than being able to go out there and focus on the match.

"I'm fighting against two things -- my arm and my opponent."

In wasn't such a great day for the tournament's second seed however, as Nicolas Massu of Chile came from a set down to upset Roger Federer of Switzerland 6-7 6-1 6-3.

Federer has been struggling recently, losing in the opening round in four of his past five tournaments.

"I've lost all confidence lately," he explained. "I feel like I'm missing energy. I started the year well, but after that it's mainly been downhill, and I really can't explain why."

Three other seeds were also knocked out in the second round, with Thailand's Paradorn Srichaphan continuing his run of good form with a 7-6 7-5 victory over eighth seed Nicolas Lapentti of Ecuador.

Flavio Saretta overcame German sixth seed Rainer Schuettler 6-3 6-3 and 12th seed Stefan Koubek fell to local favourite Jan-Michael Gambill by a 6-4 3-6 6-3 margin.

There was better news for some of the tournament's seeded players as number 11 Jarkko Nieminen beat Kevin Kim 4-6 6-3 6-1, number 14 Arnaud Clement eased past Jan Vacek 6-2 6-3, and 16th seed Agustin Calleri defeated Vince Spadea 6-2 6-3.

Other winners on the day were Jonas Bjorkamn and Mardy Fish.