Robert Yim of Glendale knows the look, the one his opponents get when they grow frustrated.
"They look down," Yim said. "They throw their rackets. That kind of stuff."
As one of the best 14-and-under players in Southern California, Yim sees that exasperated look across the net fairly often. It was in evidence on Wednesday when he defeated Mark Contreras of Temple City, 6-2, 6-1, in the round of 32 at the Southern California Junior Sectional Championships.
Most top juniors in the area have gathered for this tournament, a qualifier for the USTA national championships later this summer. Yim, third seeded in his age division, brought an array of skills:
A steady backhand. A top-spin forehand that packs surprising force for a kid who stands a shade over five feet. And the quickness that puts him in position to use those shots.
It is a frustrating combination to face.
"He had a lot of good returns of serve, too," Contreras said. "He just had it today."
Yim has had it for a long time. As a 9-year-old, he put on an exhibition that wowed Eliot Teltscher, the former No. 6-ranked player in the world, who became Yim's coach.
"I fed him some balls inside the baseline and he just about took my head off," Teltscher told The Times in 1997.
Those strokes have grown stronger now that Yim is 13.
But having made a name for himself from the baseline, Yim is trying to be more aggressive. Not yet tall enough to hit a booming serve, he looks to come in on short balls. Against Contreras, he showed a knack for hitting the deep approach, setting up a winning volley or an overhead.
"I'm trying to make my game more all-around," he said. "All-around so I can change it at different times."
Sean O'Connor of Sylmar is another player who likes to hit the ball hard, and sometimes it takes him a while to warm up.
That tendency nearly cost O'Connor in a 3-6, 7-6 (7-5), 6-1 victory over Parker Collins of Newport Beach in the boys' 18 division.
"He had me on the ropes," said O'Connor, who is seeded seventh.
The momentum turned when O'Connor gained control of his faltering backhand.
"I started making a few, started playing better," he said. "It might have intimidated him a little."
It took Jieun Jacobs of Valencia just as long to get going in a 7-5, 4-6, 6-2 victory over Natalie Braverman of Newport Beach in the girls' 16.
"I wasn't playing that smart," the sixth-seeded Jacobs said. "I was just trying to blast the ball."
Jacobs eventually succeeded by working the angles, coming to the net whenever she saw an opening. Or, as she put it, "I started thinking."
Hagop Tadevosian of Glendale upset No. 5-seeded Stefan Hardy of Santa Maria, 7-5, 6-4 in the boys' 12, and Amber Harper of Tarzana surprised No. 8-seeded Camelia Todorova of La Jolla, 4-6, 6-1, 7-5, in the girls' 12.
Darren Joe of Thousand Oaks defeated John Joseph Stewart of Pasadena, 2-6, 6-2, 7-6 (7-5), in the boys' 18. Phil Sheng of Thousand Oaks, top seeded in boys' 16, defeated Alex Yaftali of Westlake Village, 6-0, 6-0. No. 2-seeded Travis Rettenmaier of Camarillo defeated Brian Morton of Costa Mesa 6-7 (7-3), 7-6 (7-2), 6-2. Amritraj defeated Dan Nguyen of West Hills, 6-2, 6-0.
Maureen Diaz of Glendale, fourth seeded in the girls' 18, defeated Teresa Galido of Chatsworth, 6-0, 6-2. Lori Stern of Ojai, third seeded in girls' 14, defeated Joanna Kao of Fullerton 6-1, 6-2. Erica Sauer of Somis, top seeded in girls' 12, defeated Macall Harkins of Palos Verdes, 6-0, 6-0.