Los Angeles  - Top seed Tommy Haas survived an error-plagued opening set to send Marat Safin out of the Los Angeles Open Friday, entering the semi-finals with a 7-6 (7-3), 6-2 victory.

The German with two titles at UCLA from 2004 and 2006 overcame 24 unforced errors in the 64-minute opener, hanging on after saving three set points for the soon-to-retire Russian, who plans to end his career after seven more events at the Paris Masters in November.

Haas, 31, a Wimbledon semi-finalist against Roger Federer, eventually scratched to his fifth win over Safin against two losses. Haas converted on a quarter of his 16 break points in the contest lasting just under two hours.

The 29-year-old Safin was making his first appearance in an ATP quarter-final this season.

Safin managed to save five break points to open the second set with a hold as the pair of veterans who stood one (Safin) and two (Haas) in the world rankings continued their career battle.

The momentum quickly shifted in the second set, with Haas running away to victory with two breaks of the fading Russian.

Haas will line up next against American sixth seed Sam Querrey, last weekend's losing Indianapolis finalist who upset fourth seed Dudi Sela of Israel 6-3, 7-5 with the loss of just two points on his serve.

Querrey has now reached semis at his last two events, losing title matches at Newport and Indianapolis.

"It's really great to get the semi-finals here again," said Haas. "I have a tough opponent in Sam. He's playing well and he has his (Samurai) support group.

"I'll have to play well to beat him."

At the bottom of the draw, second seed Mardy Fish made a precautionary pullout with an existing abdominal strain to hand Argentine Leonardo Mayer a walkover to join another untried semi-finalist, Carsten Ball.

Australian-American Ball defeated John Isner 6-4, 6-4 with the American favouring a previously-injured right ankle but insisting it was not the cause of his downfall.

Both the 205th-ranked Ball and Mayer, former junior rivals, are into uncharted territory in their first-ever ATP semis.

Ball has never before even competed in a main draw but is trying to keep his head in potentially overwhelming circumstances. "A bit of confidence goes a long way, I was not noticing Isner today and didn't know if he was injured."

Fish had originally suffered his injury during a Davis Cup loss to Croatia nearly a month ago.

"It only bothers me on serve, but I don't want to take any chances. To be healthy is the most important thing. It's a day-to-day thing and I decided to pull out after treatment late last night."

Mayer is hoping to duplicate the feat of Argentine compatriot Juan Del Potro, who won the tournament last year. "I'm two matches away from keeping the LA trophy in home soil.

"I'm surprised to reach my first career semi-final with a withdrawal. I was ready to play today, expecting a tough match against Mardy who is a great player." (dpa)