Defending champion Andy Roddick remained the only seed remaining in the quarterfinals, although he had to save three match points against Hyung-Taik Lee.

In a match that finished just before midnight in Memphis, Roddick came through 5-7, 6-4, 7-6(3) in 2 hours, 2 minutes to book his quarterfinal berth against Robby Ginepri.

"All around the world, the fans who stay the latest are the most enthusiastic," said Roddick. "The people who stay there to the end are the die hards and I definitely appreciate it. They really pulled me through that one."

Ovation

After dropping the first set, Roddick broke the Korean's serve for the first time in the 10th game of the second to level matters, and the deciding set went with serve until Lee led 5-4 and had 15-40 on Roddick's serve. But after a service winner and a long rally that ended with Roddick hitting a forehand winner, the crowd's standing ovation lifted Roddick's spirits.

He needed them again two games later as Lee earned himself another match point, but, not for the first time, another barely touchable serve saved the day for the American.

In the tie-break, Roddick earned a mini-break on the first point and quickly opened up a 3-0, and, with his 25th ace of the match - hit at 133 mph - he kept his title hopes alive.

Clutch

"I had a bit of luck, and played some clutch points in the third," added Roddick. "I stayed in it. I'm still not feeling at my best from the baseline and I'm lucky to have a serve that can keep me in matches. I don't think I could have got through that match if I hadn't had those tough matches in Australia."

With six Americans through to the quarterfinals, Roddick said: "It's very positive. It would have been nice to have even more, and it could if some hadn't had to play each other."

And looking forward to playing his countryman Ginepri, against whom he leads 1-0 in ATP matches, he added: "I played him for the first time when I was 11 years old, and that was in Nashville. I've played him in Knoxville and now Memphis. We're very good friends and have been for a long time. But I still want to beat him."