When he wasn't yelling at himself and breaking two rackets, defending champion Sam Querrey kept it together long enough to beat Rainer Schuettler 6-2, 3-6, 7-6 (7) in the quarterfinals of the Farmers Classic on Friday.

The second-seeded American used back-to-back big serves in the tiebreaker to win at the Los Angeles Tennis Center on the UCLA campus.

Mostly, though, Querrey was disgusted with his serve, having practiced it very little since Wimbledon. It showed with nine double faults.

"My serve (stinks) right now," he said. "I don't have that consistency of that knee bend and fluid motion. It's getting better every day, though. The movement and speed around the court is really helping me win matches."

The sun affected both players when they served on one side of the court.

"It was always in the eyes," Schuettler said.

Schuettler, the oldest player in the singles draw at 34, twice served for the match in the third, but then committed three key unforced errors in the tiebreaker to lose.

"I played a little bit too defensive," the German said.

Querrey, who already has three titles this year on three different surfaces, improved to 6-0 in quarterfinal matches. In Saturday's semifinals, he'll face sixth-seeded Janko Tipsarevic of Serbia, who beat No. 3 Marcos Baghdatis 6-3, 7-5 for his first win in three meetings.

"This week I'm playing good," Tipsarevic said. "I didn't drop a set yet."

Top-seeded Andy Murray beat Alejandro Falla of Colombia 7-6 (7), 6-1 to set up a semifinal against No. 4 Feliciano Lopez of Spain.

Murray served it out and hit a forehand winner after an ace set up his second match point. Back-to-back big serves gave him his first match point before he committed a backhand error.

"It was a tricky match," Murray said. "Alejandro has been playing well the last two months. I played well, but it was difficult conditions — pretty cold, I hit a lot of balls in the net, I felt pretty slow."

At times, Murray grabbed his right knee and wore pained expressions on his face.

"It's a bit sore, just from not playing," he said. "Obviously, a huge difference playing on the grass and obviously coming to the hardcourts."

Lopez outlasted wild-card James Blake 3-6, 7-6 (8), 6-4. Blake double-faulted to lose the second set, then unsuccessfully challenged a sideline call on match point and lost.

"My serve started to let me down," Blake said. "I wasn't hitting my spots, that put a little more pressure on me. I didn't play enough of the big points at the end of the second set with conviction."

Against Querrey, Schuettler didn't face a break point in the third until the 10th game. He lost his serve on a net cord forehand that pulled Querrey into a 5-5 tie.

The 22-year-old American, the youngest player left in the tournament, got broken in the next game and Schuettler had a chance to serve out the match. But he fell behind 15-40, then netted a forehand to force the tiebreaker.

Querrey led 4-1 before Schuettler closed to 4-3 on Querrey's backhand error. Querrey came up with a big service winner, then sent an ace down the middle for a 6-3 lead. Schuettler answered with his own ace before another backhand error gave away the match.

"I was a mental head case out there. I still got through it," Querrey said. "I need to somehow figure out how not to do that out there. I was Debbie Downer."