West German tennis and Boris Becker are not synonymous, although he did give it a good boost by winning Wimbledon last summer.

"Tennis is right now maybe the main sport, even before soccer, because of Becker," said Claudia Kohde-Kilsch, West Germany's top female player. "But the women were playing well before that and had much popularity, but now it's more so."

Sylvia Hanika and Bettina Bunge were ranked as high as fifth and sixth, respectively, in 1983, and 16-year-old Steffi Graf -- who is popular enough to charge a fee for interviews in Europe -- now is ranked sixth. One spot ahead of her is Kohde-Kilsch, who didn't hurt that ranking any yesterday when she beat Wendy Turnbull, 6-4, 6-4, in the second round of the Virginia Slims of Washington at George Washington University's Smith Center.

Top-seeded Martina Navratilova, though never really in danger, had an early challenge from Susan Sloane before beating the 15-year-old from Lexington, Ky., 6-3, 6-1.

Sloane, 241st in the world, gave the crowd a bit of a thrill by winning the first game and then holding for a 2-1 lead, which was her last.

"She played really well," Navratilova said to the crowd after each player was presented with a flower. "I hope that by the time she reaches her peak, I'll be out of the game."

Later, Navratilova said, "I wasn't quite ready to play. It all snuck up on me. I wasn't sharp until about the fourth or fifth game."

Sixth-seeded Helena Sukova also advanced to the quarterfinals -- in which she will face fourth-seeded Manuela Maleeva -- by defeating Sabrina Goles, 6-0, 6-4.

Turnbull and Kohde-Kilsch have a history of playing close matches. Kohde-Kilsch now leads their series, 4-3, after winning their first meeting and the last three. In the fourth round of the 1985 U.S. Open, Kohde-Kilsch won, 5-7, 7-5, 6-2, and then in the quarterfinals of the Australian Open, she won, 6-7 (4-7), 6-3, 6-1. Yesterday's match, although a set shorter, was no less close.

Kohde-Kilsch is the third seeded player in this tournament, but Turnbull looked like the favorite in the first three games, all of which she won. Actually, Kohde-Kilsch lost the second game by double-faulting three times. She double faulted 10 times in the match, but only three in the second set.

"I didn't have my rhythm on my second serves," she said. "I didn't hit the ball high enough. In the second set it was going better. But I did double-fault on two game points."

Kohde-Kilsch's coach, Olaf Merkel, said that, although yesterday's performance might not indicate it, her serve has improved.

"She had a big problem," Merkel said. "A year ago, 10 double faults would be good. We worked on the serve and changed some things and for the last year one, two or three is the average."

Kohde-Kilsch is 6 feet one-half inch and likes to come to the net where she can use her range. But yesterday, Turnbull was at the net much more, and the fact that Kohde-Kilsch won despite not playing her usual style is an indication of why she is in the top five.

"We always have tough matches, because she's very fast and good at the net," Kohde-Kilsch said. "If I hadn't passed as well on my backhand, it would have been tougher.

"She knows how to hit to me. I decided to mix it up, and my passing shots were good . . . . "

Her stepfather, Jurgen Kilsch, has played a prominent role in her tennis career.

Several years ago she added his name to Kohde, the name of her natural father, who was divorced from her mother when Claudia was 3. "I've known my stepfather since I was 3, so he's my father," she said.

Kilsch travels with her and assists in her training, which has helped her footwork and, in turn, helped her be a better baseline player.

"I've been working on the footwork with my father for the last two years and it's paid off," she said. "I have to work on short sprints because I'm very tall. If you're small, you can turn faster, but I have to work on that. Now, it's hard to hit a ball I can't get to."

That is probably exactly what Turnbull was thinking in the fourth game of the first set. Kohde-Kilsch chased down a ball in the corner to her left. Turnbull tried a drop volley near the sideline in the open court, but Kohde-Kilsch planted, ran cross-court and hit a forehand passing shot down the line.

"Maybe, she was surprised I got to the ball," Kohde-Kilsch said.

Merkel thinks she is an excellent baseline player, but, to be No. 1, she has to expand.

"She is a great baseline player," Merkel said. "Maybe not Chris (Evert Lloyd), but she can beat anybody else from the baseline. But she didn't play with the right mix of baseline and going to the net . . . . To get close to the top two, you have to play without weakness and you have to be as smart as they are and handle every situation."

Turnbull's day wasn't a total loss. She teamed with Candy Reynolds to defeat Paula Smith and Robin White, 6-1, 6-7 (3-7), 6-3.

Maleeva and her sister, Katerina, were eliminated from the doubles by Elise Burgin and Kathy Jordan, 7-6 (7-4), 6-0. Betsy Nagelsen and Barbara Potter beat the Soviet doubles team of Svetlana Parkhomenko and Larissa Savchenko, 6-2, 6-4.

Navratilova and Pam Shriver beat Pascale Paradis and Marcella Mesker, 6-3, 6-2. Zina Garrison and Kathy Rinaldi defeated Carling Bassett and Bonnie Gadusek, 6-4, 6-3.

TODAY'S SCHEDULE Morning session (11 a.m.)

Candy Reynolds-Wendy Turnbull vs. Elise Burgin-Kathy Jordan; Helena Sukova (6) vs. Manuela Maleeva (4). Evening session (6:30 p.m.)

Bettina Bunge vs. Kathy Rinaldi (8); Bonnie Gadusek (7) vs. Pam Shriver (2); Claudia Kohde-Kilsch-Helena Sukova vs. Zina Garrison-Kathy Rinaldi