No. 1 Seles a Perfect 10 Against No. 5 : Tennis: She has trouble with her groundstrokes and serve, but Sanchez Vicario is no problem.

If this were baseball, you could simply pitch around her. But this is tennis, and Monica Seles is the only one on the other side of the net. So, you have no choice but to hit it to her.

And she is happy to stay on the baseline and take batting practice, slugging the ball into the corners for winners.

Saturday, Arantxa Sanchez Vicario watched Seles’ groundstrokes whistle past her, losing, 6-3, 6-2, to the world’s top women’s player in the semifinals of the Virginia Slims of Los Angeles at the Manhattan Country Club.

Seles, shunning the serve-and-volley game, is content to play on the baseline for one reason: She keeps winning that way.

She says she would like to mix in a few more approaches to the net, but it’s no big deal. If it ain’t broke . . . well, you know the rest.

“I think Steffi (Graf) is beating everybody staying back,” Seles said. “Why does Martina (Navratilova) serve-and-volley? That’s her game. You do whatever is best for you.”

Sanchez Vicario is a virtual expert on Seles. Ranked No. 5 in the world, she has played Seles 10 times and lost to Seles 10 times.

The last time they met, in the final of the International Championships of Spain in April, Sanchez Vicario won the first set, then lost the next two in front of a home crowd.

“I don’t think at all that I’ve lost to her nine times . . . well, 10 now,” said Sanchez Vicario, who has won only three sets against Seles. “Every match is different. I just keep improving match after match, moving in the right direction. I know what I have to do.”

One of the things she will have to do is make fewer unforced errors. She had 42--plus 12 forced errors--Saturday. “I just didn’t hit the ball so well,” Sanchez Vicario said.

Seles had something to do with that, as she did in her quarterfinal victory over Amy Frazier, who made 23 unforced errors.

“You know you have to take advantage of opportunities, and maybe you think about it too much before you hit (the ball),” Sanchez Vicario said.

Although Seles won with relative ease--the match took 63 minutes--she played less than her best tennis.

Seles, who hit only 12 winners, said her groundstrokes needed work and she had trouble with her serve because of the sun, putting only 53% of her first serves in play.

“I just want to forget (about this match),” she said.

Although Sanchez Vicario agreed that the match was forgettable, there was a slight difference of opinion on Seles’ play.

“She’s not missing easy shots, so you have to play every point really well,” Sanchez Vicario said. “That’s why she’s the No. 1 player in the world.”

Seles, 18, whose career earnings are more than $5.5 million, took over the No. 1 ranking on March 11, 1991, and has held it continuously since Dec. 1, 1991.

She said there is pressure being at the top, but tries not to let it bother her. “I don’t wake up in the morning and say, ‘Oh, I’m No. 1 in the world. What a wonderful life,’ ” she said. “No. 1 is a big thing when you get it or you lose it, but while you’re there, it’s just there.”

So far this year, she has played 50 matches and lost three.

And contrary to what the British reporters who followed her around at Wimbledon might say, the now-famous grunt apparently has nothing to do with it. She has been quiet all week.

So, Monica, how do you beat Monica Seles?

“I don’t know,” she said.

She’s not alone.