Atlanta (Georgia), Jul 24 (DPA): Andy Roddick repeated a victory from 2001 as he struggled past Belgian Xavier Malisse 4-6, 6-3, 6-4 to reach the semi-finals of the Atlanta Tennis Championships.

Nearly a decade ago, Roddick claimed the first ATP title of his career as he beat Malisse in the final at the event, which was cancelled and came back to life this week on the Tour.

The win Friday lifted top seed Roddick to an ATP-leading 28-4 on hardcourt this season during the first of the US Open countdown weeks in North America.

Roddick dropped the first set on a break in the seventh game in which he saved five break points and produced the same number of aces before losing his serve.

But after dropping the opener three games later, the winner of 29 titles began to turn the tide, and finally earned the victory after more than two hours with 17 aces.

It was his ninth without a loss to Malisse, ranked 57th, who turned 30 this week.

"Nothing felt comfortable in the first set, but I tried to get aggressive, I wanted to grind back," said the American. "Xavier played well - he let me off the hook a bit.

"I started swinging at my forehand more and it got better at the end."

Second seed John Isner set up a grudge rematch from his university days as he moved into a semi-final against long-time rival Kevin Anderson with a victory in steaming heat.

Second seed Isner, winner of the longest match ever played in tennis - 11 hours in the Wimbledon first round - needed only 58 minutes to escape the 48-degree-Celsius on-court hothouse conditions with a defeat of fellow American Michael Russell 6-1, 6-2.

Anderson, a South African who played at an American university before turning pro, booked his place in equally impressive fashion, putting out Slovak Lukas Lacko 6-3, 6-4.

Number 19 Isner is keen for his match with Anderson, ranked 96th without a career title.

"I remember I took him out when we played Illinois for the (university) championship," said Isner. "He's playing well now, he's rolled through the tournament.

"He has a huge serve and forehand, it will be tough."

Isner said he's trying to put aside his Wimbledon footnote to concentrate on the future. "I felt better today than I did in my first match.

"I knew that I would need to play better - even in this ridiculous heat."

Isner found just 11 aces in victory, a portion of more than 20 winners.

He said that the US Open starting Aug 30 is his next big goal as the number two American behind Roddick.

"I'm back to hardcourt, which is my favourite surface," said the 25-year-old. "I want to focus on doing well over the summer. I think that Wimbledon made me a better player.

"But the bottom line is that I did lose in the second round there."