Bonnie Gadusek beat Kathy Rinaldi at her own game Sunday.
Hitting steady base-line shots, she defeated her 18-year-old opponent, 6-1, 6-3, to win the $150,000 Virginia Slims tournament at Chicago.
It was the third championship of the season for Gadusek, who earned $27,000 to Rinaldi's $13,600.
In beating Rinaldi for the first time in three career matches, Gadusek was consistently able to get her first serve in, while Rinaldi wasn't.
When Rinaldi was down 5-1 in the first set, she changed her style slightly, taking an occasional opportunity to go to the net, which she seldom does. It worked occasionally but she also made errors on approach shots.
In the second set, however, Gadusek capitalized on Rinaldi's mistakes.
"I think I made quite a few unforced errors," Rinaldi said. "She played very well and pressured me all around the court."
With Gadusek ahead 3-2 in the second set, Rinaldi took a love-40 advantage in the sixth game, but Gadusek came back to win five straight points for a 4-2 lead.
"When I'm down I think 'go for it,' " said the 22-year-old Gadusek. "I felt I could handle her pace throughout the match. I felt like I could outsteady her."
Gadusek said she benefitted from a change in coaches. She started working with Gene Malin from Los Angeles.
"I thought I played fairly poorly in the U.S. Open," Gadusek said. "He (Malin) made a difference this week and last week (during an exhibition tournament)."
In the doubles final, Kathy Jordan and Elizabeth Smylie beat Elise Burgin and JoAnne Russell, 6-2, 6-2.
At Geneva, Tomas Smid of Czechoslovakia upset top-seeded Mats Wilander of Sweden, 6-4, 6-4, to win the $100,000 Martini Open.
It was Smid's first victory in a Grand Prix final in more than two years.
Smid, 29, played more aggressively than Wilander, scoring a number of winners on his sliced backhands and passing shots.
In the first set, Smid broke Wilander's serve for a 5-4 lead, and then won the set on his own serve. In the second set, the decisive break came in the fourth game when Smid took a 3-1 lead.
Wilander had three break points in the first set and one in the second, but Smid saved them all.
At Bordeaux, France, Diego Perez of Uruguay beat Jimmy Brown, 6-4, 7-6, to win the $100,000 Nabisco Grand Prix, his first-ever Grand Prix victory.