Rotterdam, Netherlands – Roger Federer suffered through an uncharacteristically error-filled display Friday to exit in the quarter-finals of the Rotterdam World Tennis, a 6-3, 7-5 upset victim of Frenchman Julien Benneteau.

The top seeded Federer had won the last two editions that he had played in the Dutch port city and suffered his last loss in a 2004

quarter-final against Tim Henman.

The Swiss legend lost serve three times in the opening set and trailed 4-1 in the second. He managed to break back for 4-all only to eventually miss a chance to take it into a third.

Benneteau, loser of four of five previous matches to Federer, saved three break points in the penultimate game and then ended the upset as he broke the Swiss once more to complete the job.

“I am very disappointed. I have some regrets about this match,” Federer said. “He played great and created more chances than I did. He deserved to win. It was a tough loss, but they do happen. Being broken so many times (five) indoors won't get the job done.”

Federer said that Benneteau's pressure made him try to serve harder: “When I had some chances I didn't take them. I was maybe a point or two away from taking it into a third set.”

Benneteau called it a “dream match.”

“And I played like a dream,” he said. “This is for sure my biggest win. He was the favourite, but maybe he played a bit tight. I've been playing well all week, improving with each match.”

Benneteau earned a semi-final against fifth-seeded compatriot Gilles Simon, who advanced as Slovak Martin Klizan retired to yield a 6-7 (6-8), 6-3, 3-0 win for the Frenchman.

Second seed Juan Del Potro stayed on course with an efficient 6-3, 6-4 defeat of Finn Jarkko Nieminen.

The Argentine will next face a challenge from Bulgarian Grigor Dimitrov, who earned a second win in as many months over Marcos Baghdatis as he defeated the Cypriot 6-7 (4-7), 7-6 (7-0), 6-3 in their quarter-final.

Del Potro lost the title match a year ago to Federer.

The Argentine won against Nieminen as he played in his first quarter-final of the season after a third-round loss in the Australian Open. Del Potro is aiming to win a 14th career ATP trophy as he plays Rotterdam for the second time.

He and Dimitrov have never faced off on court, though they have trained together on occasion.

Del Potro spent almost 90 minutes in holding off Nieminen, firing 10 aces and winning on a second match point.

“It was a difficult win. In the second set he played well, with lots of rallies. I was just holding on, waiting for my chance to break him. It finally came in the last game,” Del Potro said.

“It feels good to be in the semi-finals. I'm trying to repeat what I did last year (reaching the final) and go even farther. Dimitrov has a very good future. He's playing fantastic tennis. The match will be close for both sides.”

Dimitrov, losing finalist last month in Brisbane and a winner at that event over Baghdatis in the semi-finals, won a string of 18

points in a row from the final game of the second set, through a tiebreaker and into the third set.

Del Potro would be a “tough match,” Dimitrov said.

“He's in the top 10,” Dimitrov noted. “I have to expect everything from him. I have half a day to prepare. I just hope to be ready physically and mentally for the match. I'll have to compete all the way through if I want to have a chance.” – Sapa-dpa