Top seed Andy Roddick survived a battle against Yen-Hsun Lu of Taiwan on Friday to set up a mouthwatering semi-final clash with Andy Murray at the Memphis International.

Roddick came back from 5-2 down in the second set to clinch a 6-4, 7-6 win over world number 90 Lu after third seed Murray enjoyed a much more comfortable passage with a 6-3, 6-2 victory over Austrian Stefan Koubek.

Murray beat Roddick in straight sets in the semi-finals of the San Jose Open in California last weekend on the way to winning the title.

Lu, appearing in his first ATP Tour quarter-final, led 5-2 in the second set and had four set points in the tiebreak, double-faulting on the third, as a relieved Roddick claimed his place in the last four.

"It's a frustrating dynamic to feel like you're on the verge of playing well but you're just not quite there and that's what I've been battling for the last two weeks," Roddick told reporters.

"I feel like I am striking the ball well, I just don't know if I am constructing the points as well as I normally do."

The former world number one has lost three of his four meetings with Murray.

"He's tough and he's playing with a lot of confidence right now," he said. "He plays defence so well and he is not as affected by pace. He moves well and he doesn't play himself out of points."

Murray cruised to victory over Koubek, reaching the semi-finals for the third time in four events this year and extending his winning streak to eight matches.

He has now won 15 of his 17 matches, a mark he did not reach in 2006 until Wimbledon.

"That's the best match I have played so far," Murray said. "I hit the ball really well from the ground, didn't make too many unforced errors and took my chances when I had them.

"That's two matches in a row where I haven't dropped my serve and that's a good run to be on."

STRONG SERVES

The Austrian's only chance came when he forced two break points in the fourth game but Murray shut the door with two strong serves before breaking in the next game and easing to victory on his third match point.

Murray said he felt he would still be the underdog against Roddick.

"I still say he is the favourite," Murray said. "He is number four in the world, has won a grand slam and has been number one. For me to win against a guy like that is still a huge result.

"But I feel like I read his serve pretty well and don't get aced that often by him. It is important that I take the chances when he does miss his first serve and then dictate play from the baseline."

Holder Tommy Haas produced a stunning performance to beat American wildcard Sam Querrey 6-2, 6-2.

The second-seeded German dropped only six points on serve as he wrapped up victory in 44 minutes to set up a meeting with fourth-seeded American Mardy Fish.

"I knew I had to serve really well," Haas said. "When I got a break right away I got the momentum and felt pretty solid throughout."

World number 25 Fish reached his second semi of the year when Russian Teimuraz Gabashvili retired, trailing 6-2 4-1, because of the viral illness that has affected several players at the tournament.

It was the first time the top four seeds have qualified for the semi-finals of an ATP event since Vina del Mar, Chile, in 2005.