Atlanta: John Isner kept his Atlanta ATP title defense on track Friday with a 7-6 (10/8), 6-4 quarter-final victory over Australian Marinko Matosevic.
A day after Isner fired 30 aces and still had to fight off two match points in a second-round win over Robby Ginepri, the towering American fired 17 aces and won 84 percent of his first-serve points in his win over Matosevic.
Isner was broken in the first game of the match, but kept his composure to take the opening set in a tie-break, saving a set point along the way.
He converted two of his own five break chances to seal the win, breaking for a 4-3 lead in the second set and pounding an ace on his first match point.
"I knew he was struggling out there a little bit and he knew I was struggling out there a little bit," Isner said. "A lot of times those situations are a big advantage for me because I can muster up enough energy to pop some big serves in.
"The beginning of the second set it felt like someone put us in the oven. It was rough. There`s only one option for me there: play big and play aggressive. A lot of times it works out."
Isner, the champion in Atlanta in 2013 and runner-up to Mardy Fish in both 2010 and 2011, will face fellow American Jack Sock for a place in the final.
Sock rallied from an early 1-4 deficit to dispatch Slovakian Lukas Lacko 7-6 (8/6), 6-2.
Sock, enjoying the best season of his career, was in his fifth quarter-final of 2014.
"I had a pretty rough start," Sock said. "He came out keeping the ball really deep, keeping me off the baseline and out of my forehand. I broke back for 5-4 and the momentum shifted in my favor."
Israel`s Dudi Sela booked a semi-final berth with a 7-5, 1-6, 6-2 upset of Canadian fourth seed Vasek Pospisil.
Sela notched his 100th tour-level match win and reached the fifth ATP semi-final of his career.
He`ll face Germany`s Benjamin Becker, a 6-4, 6-2 winner over Thiemo De Bakker of the Netherlands.