Flavio Cipolla of Italy defeated Jack Sock of the United States 6-3, 6-1 in the first round at the Farmers Classic on Monday night.
A quarterfinalist last week in Atlanta, where he lost to 11th-ranked John Isner in two close sets, Sock struggled with errors and Cipolla's experience at the Los Angeles Tennis Center at UCLA.
No. 8 seed Brian Baker also made a quick exit from the tournament, losing to fellow American Rajeev Ram, 7-6 (3), 7-5, in a late match. It was the second straight first-round loss for Baker since reaching the fourth round at Wimbledon.
Sock had two aces in his opening service game and was even with Cipolla at 3-3 in the first set, then lost serve four times in five games as Cipolla controlled the 68-minute match.
"I opened up serving very well," Sock said. "I was getting free points on my serve, which is what I try to do. Then I started missing a lot of first serves and he started getting a lot of game points.
"I thought he was hitting the ball pretty well. His slice stays really low and the night takes a little bounce out of the court. I was hoping to kind of use my height and kick serves and some high, heavy forehands to get up on him, he's a short guy (5-foot-8), but he handled it well. I wasn't expecting him to be able to take every slice and keep it off the net on my forehand. He just played well tonight."
Sock struggled with errors as well. One of those, a double fault, gave Cipolla a break point to go up 5-1 in the second set, and a forehand that sailed just long on match point gave the 93rd-ranked Italian the win.
Earlier in the day, Paul Capdeville of Chile almost wasted a five-point lead in a second set tiebreaker before wrapping up a 6-4, 7-6 (5) win over Igor Kunitsyn of Russia.