MEMPHIS, Tenn. -- Top-seeded Andy Roddick lost to fellow American Sam Querrey 7-5, 3-6, 6-1 in the quarterfinals of the Regions Morgan Keegan Championships on Friday.
Roddick, No. 7 in the world ranking, was broken twice in the final set, first on a double-fault to fall behind 2-0 and two games later when a forehand volley sailed long.
Querrey, who lost to Roddick last week in San Jose, had 15 winners and only three unforced errors in the last set, winning when Roddick netted a backhand. He beat a top-10 player for the seventh time in his career.
"It was a huge win," said Querrey, who was selected for the U.S. Davis Cup team on Wednesday. "Anytime you get a top-10 win it's a really big boost for your confidence, especially against Andy. He's someone I've looked up to over the last four or five years."
Roddick, the defending Memphis champion, said his double-fault in the second game of the final set cost him.
"I played a real irresponsible game up 40-15," he said. "I missed a couple of routine shots. There's no [excuse] for that. And then I double-faulted, which is rare. There's no real defense for that."
In the women's draw -- the Cellular South Cup -- top-seeded Maria Sharapova beat No. 5 Petra Kvitova 6-4, 6-3 to reach the finals.
Sharapova, ranked No. 16 in the world, next plays 2006 champion Sofia Arvidsson, who had to qualify for the event. Arvidsson advanced with a 6-4, 4-6, 6-4 victory over Britain's Anne Keothavong and is seeking her second career WTA Tour title.
Also in the men's quarters, unseeded Ernests Gulbis of Latvia upset No. 5 Tomas Berdych of the Czech Republic, 3-6, 6-3, 7-6 (3), and No. 6 John Isner beat Croatian Ivo Karlovic 6-1, 7-6 (7). German Philipp Petzschner defeated Lukas Lacko of Slovakia 6-1, 1-6, 6-1.
Gulbis sought treatment for a knee injury during the third set, then rallied for the win. He broke Berdych at 5-3 to get back in the match and won the final four points in the tiebreaker, finishing it off with his 23rd ace.
"I just played more relaxed," Gulbis said. "I had nothing to lose."