John Isner struggled for nearly three hours as he held off good friend and doubles partner James Blake 7-6 (10/8), 6-7 (3/7), 7-5 on Wednesday to reach the quarter-finals of the ATP Atlanta Championships.
Isner piled on 30 aces in his battle, which looked to be shaping up as a straight-sets stroll when he led by a set and 4-1.
Blake, however, had other ideas and made his Florida neighbor fight for the win.
Isner, the third seed who finished runner-up here last year to Mardy Fish, finally secured victory after a break in the penultimate game of the third set, holding his own serve to finish it out.
"There are no secrets when James and I play," Isner said. "I drive my golf cart to his house pretty much every day. We practise with each other all the time so I know him well.
"It came down to a few points here and there."
Isner will face off on Friday against Taiwan's Lu Yen-hsun, who rallied to beat Bosnian-born Australian Marinko Matosevic 3-6, 6-1, 6-2.
South African second seed Kevin Anderson continued the best season of his career, downing Michael Russell 6-1, 7-5.
He will play Friday against Gilles Muller of Luxembourg, who notched 15 aces in a 7-6 (8/6), 2-6, 6-2 victory over Robby Ginepri, who is trying to come back from the broken elbow he suffered in a mountain bike crash last year.
Anderson, 25 and ranked ranked 34th in the world, won a title on home turf in Johannesburg this season. Against Russell he needed less than 90 minutes to book his sixth quarter-final of 2011.
"This season is the result of a lot of hard work," said Anderson, who has climbed some 100 spots in the world rankings in the last 18 months and captured his first career title.
"I'm clearer on how I want to be playing. I've learned a lot playing higher-ranked opponents.
"I now have more belief no matter who is on the other side of the net. I'm working on movement, coming to the net more and trying to dictate. I want to do everything possible to allow myself to play my best tennis."
Anderson's big serve produced 10 aces as he broke Russell four times while dropping his own serve once.
The steamy summer conditions did not make life any easier for Anderson.
But the weather was cool compared to the scorching temperatures of last years's inaugural edition.
"It was definitely more comfortable today than last year. But the heat is still there and you have to manage yourself."