NEW HAVEN, Conn. -- Top-seeded Fernando Verdasco beat Dudi Sela 6-4, 6-4 to advance to the quarterfinals of the Pilot Pen tournament Monday night.
Verdasco, ranked No. 13 in the world, had a bye into the second round. He also reached the quarterfinals of this tournament in 2005 and 2007.
Seventh-seeded Alize Cornet eliminated Nicole Vaidisova 6-3, 7-6 (8) in a first-round match. Cornet also defeated Vaidisova at the Beijing Olympics.
Juan Martin Del Potro, who has won four straight times on the ATP Tour, withdrew from the Pilot Pen tournament Monday, citing exhaustion.
Del Potro, ranked 17th in the world and seeded third at New Haven, was coming off tournament victories in Stuttgart, Germany, Kitzbuhel, Austria, Los Angeles and Washington, where he won the championship match Sunday. He had been scheduled to play Tuesday.
"It is difficult to still play a lot of matches," Del Potro said. "I want to recover for the U.S. Open. Unfortunately I have to pull out of this tournament."
The U.S. Open begins next week.
Del Potro attributed his success in the last four tournaments to being relaxed on the court.
"I am living a dream," he said.
Jesse Levine will take his place in the main draw.
On the court Monday, promising young American player John Isner defeated Igor Kunitsyn 6-4, 6-4 to advance to the second round.
The hard-serving Isner closed out the match with a 135 mph serve, but said the key to victory was throwing in some changeups.
"I tried a different strategy," Isner said. "I didn't go for the big bomb every time. I thought I'd try some different things heading into the (U.S.) Open."
