US top seed Andy Roddick captured his 500th career victory on Thursday, defeating countryman Sam Querrey 7-6 (7/4), 6-4 to reach the quarter-finals of the ATP Washington Classic.

Roddick became the 36th Open-Era player to reach 500 match wins and only the fourth active player at that mark, the ninth-year professional joining Federer with 657, Spain’s Carlos Moya on 573 and Australian Lleyton Hewitt with 511.

“That’s kind of a milestone in tennis,” Roddick said. “It’s a very humbling experience. Who knows? We might try for 500 more.”

Fifth-ranked Roddick, who turns 27 later this month, won his only Grand Slam title at the 2003 US Open. He seeks his 29th career crown and fourth in Washington after titles in 2001, 2005 and 2007.

Roddick, in his first event since losing a five-set thriller to Roger Federer in last month’s Wimbledon final, will play big-serving Croatian Ivo Karlovic for a semi-final spot in the $1.4 million hardcourt event.

Roddick won four of the last five points in the tie-breaker and broke Querrey in the third game of the second set, then rescued two break points in the final game of the match, winning when Querrey sent a backhand long after 95 minutes.

Querrey, ranked 26th, has been sizzling the past month, reaching the finals at Newport and Indianapolis and winning last week’s title at Los Angeles. He ranks third in ATP aces this season, trailing only leader Karlovic and Roddick.

Karlovic ended the dream run of India qualifier Somdev Devvarman 7-5, 6-1.

Karlovic fired 14 aces, 11 in the first set, and connected on 63 percent of his first serves to beat Devvarman, who hit 70 percent of his first serves but was broken in the last game of the first set and twice in the second set.

“It’s really hard to break his serve when he is serving that well,” said Devvarman. “I was doing well and then he got the break. Momentum went his way after that.”

Devvarman will jump about 10 spots in the rankings to 143rd after reaching a career-high of 127 last month.

“I feel like the summer started on the right note,” he said.

Former world number ones Hewitt and Juan Carlos Ferrero of Spain were both ousted in three sets.

Defending champion and second seed Juan Martin Del Potro of Argentina outlasted Hewitt 4-6, 6-3, 7-6 (7/2) to avenge a straight-set loss to the 42nd-ranked Aussie in the second round this year at Wimbledon.

Hewitt, who fired 13 aces, rode an early break to the first-set victory but squandered a 40-15 lead in the seventh game of the second set to surrender a break that cost him the set.

Del Potro, who smashed 18 aces, served for the match at 5-4 but Hewitt broke him at love and forced the tie-breaker, where Del Potro won the final five points, taking the last two on Hewitt’s serve when the Aussie netted backhands.

“It’s always tough to play Lleyton,” Del Potro said. “That game (at 5-4) was tough. I was thinking too much. I missed easy balls. Lleyton came back very good. I refocused. In the tie-breaker I played better. That was the key.”

Tommy Haas blasted 19 aces to defeat Ferrero 7-5, 2-6, 6-1. The 31-year-old German improved to 18-4 since May in a run that includes a title at Halle and a Wimbledon semi-final run before losing to Roger Federer.

“I’m really happy with the win,” Haas said. “The last few months I’ve played some of my best tennis. If you keep motivated and injury-free, there’s no reason you can’t play your best at 31 or 32. Age is just a number.”

Haas faces Chilean fourth seed Fernando Gonzalez in the quarter-finals, the winner to face either Del Potro or Swedish fifth seed Robin Soderling.