Wheaton Serves Up a Victory : Tennis: His ranking has fallen to No. 44, so he tries something new in a first-round win over Stark at UCLA.

You’re 23, you’re ranked No. 44, you were No. 12 a year ago and for the first time in your life you feel as if you’re one of the hunted.

What have you been doing, David Wheaton?

Taking two months off and working on your serve?

Actually, yes. Even though his ranking has gone south on him, Wheaton believes it will be only a matter of time before his new serve flattens itself out like it used to, the ball skids off into the shadows and he doesn’t have to worry if he did the right thing.

“I knew it was going to be a gamble, I just hope it’s a good gamble,” Wheaton said.

In his opening match Monday at the Volvo/Los Angeles tournament, Wheaton’s serve was both hard and flat, at least according to the player who had to hit it back.

“It looked pretty good to me,” said Jonathan Stark, who lost to Wheaton, 7-5, 6-3, at the Los Angeles Tennis Center at UCLA.

While it was not exactly a resounding example of his overpowering service--three aces and three double-faults--Wheaton thinks his two months he spent this spring at Saddlebrook and the work on his serve will start paying off.

Wheaton found himself starting to spin the ball on his serve instead of hitting it hard and flat, so he decided a change was necessary after losing in the fourth round at Wimbledon. A year ago, he was a semifinalist there and two weeks later reached No. 12 in the rankings.

The rest of 1991 was pretty good, too, including a fourth-round result at the U.S. Open and a victory good for the sport’s biggest payday--$2 million for winning the Grand Slam Cup.

But Wheaton felt he needed to make some changes in his game, even if his ranking would suffer, which it has.

So why go through it?

“I’m trying to build a future, not get in and get out, so I’ve had to learn a few things,” Wheaton said. “This year, things have gotten tougher when I play. They know you’re a big win as opposed to when you’re the one who is head-hunting out there.

“I guess it’s going to take me a while to reach my peak,” he said.

Wheaton, who meets either Jeff Tarango or wild card Michael Joyce in the second round, is only 18-14 this year. But he said he expected some problems on the court.

“With two months off, then working on my serve, I knew my ranking was going to drop,” he said. “Now that it’s happening, you say ‘Gee, maybe I should have kept my game.’ ”

Tennis notes

Derrick Rostagno, who admires a good wave as much as a good serve, seemed to have a swell time in his first-round match. The fifth-seeded player has dropped from No. 13 to No. 27 in the few last months, but looked sharp in a 6-3, 6-4 over Danilo Marcelino of Brazil. Afterward, Rostagno identified his favorite surf as the one that washes at Baja, a couple of hours south of Ensenada. More specific: “Out where there’s nothing.” . . . In a night match, Brad Gilbert defeated Jim Grabb, 6-4, 3-6, 6-1. . . . Bjorn Borg, 36, plays Chris Pridham this afternoon in a first-round match. Pridham is ranked No. 113. Borg’s ranking improved from 920 to No. 917 this week. . . . Jimmy Connors, who will be 40 in a month, plays qualifier Dave Randall of Birmingham, Ala., in the night match. Connors is ranked No. 42, Randall No. 385.