Justin Gimelstob is probably best known for being the mixed doubles partner of Venus Williams, who teamed with Gimelstob to win titles last year at the Australian Open and French Open.

Soon, though, fans might get to know Gimelstob for his accomplishments playing singles.

Gimelstob, a 22-year-old from Miami, took another step in that direction yesterday, defeating 15th-seeded Richard Fromberg, 6-4, 2-6, 7-6 (7-4), in the first round of the Legg Mason Tennis Classic at the William H.G. FitzGerald Tennis Center in Northwest Washington.

It was Gimelstob's second upset in a week. In the ATP Championship last week in Mason, Ohio, Gimelstob defeated seventh-ranked Todd Martin in the second round.

"I think people recognize me from [playing mixed doubles], but hopefully it will be more and more for my singles," said Gimelstob, who is ranked 91st in the world.

After yesterday's match, Gimelstob spent more than an hour in the training room trying to work out cramps in his right leg.

Gimelstob had an opportunity to finish off his Australian opponent before the tiebreaker, serving at 5-3 in the third set. Leading 40-15, though, Gimelstob failed to convert either of his two match points and lost the game.

The players held serve the rest of the set to force a tiebreaker, and Fromberg led 3-2 before Gimelstob took over.

Using his hard-charging style, Gimelstob won four consecutive points to take a 6-3 lead. He finished the match with a backhand volley into the open court, then dropped to his knees and raised his hands in celebration while facing several family members who had come from New Jersey. Gimelstob's uncle, former George Washington men's basketball coach Gerry Gimelstob, also was in the stands.

"I was really relieved just to get through it," Justin Gimelstob said. "I'd had some opportunities to close it out much earlier."

Despite losing, Fromberg was pleased with his play. He had been sidelined with a broken wrist and was playing in just his second tournament of the year on hard courts.

"I arrived Thursday night and didn't practice until Saturday afternoon," Fromberg said, explaining that he needed rest to shake off jet lag. "I'm quite happy with the way I hit the ball."

Gimelstob will play another Australian, Wayne Arthurs, in the second round. Arthurs defeated 25-year-old Crofton resident Patrick Osuna, 6-1, 6-4.

Osuna had earned a berth in the field by winning the Wild Card Challenge earlier in the summer, a tournament in which local players vie for one berth in the field.

Yesterday, though, Osuna had difficulty with Arthurs's booming serve. The 28-year-old Australian had 15 aces and won 21 of the 22 points in which he made his first serve.

"It's definitely a reality check just to see how good these guys really are," said Osuna, adding that he enjoyed being in the field. "I've seen a lot of familiar faces and had a lot of familiar people come up to me and say hi. It's been real nice."

Pless, Washington Win

Eighteen-year-old Kristian Pless was the first player to win his first-round match, taking just 52 minutes to defeat Romania's Adrian Voinea, 7-5, 6-0.

It was the first ATP Tour victory for the 18-year-old from Denmark, who is the world's top-ranked junior. Afterward, he called home to tell his father, even though it was around midnight in Denmark.

"He was awake," Pless said. "He couldn't sleep."

The match was close in the first set, with both players holding serve until 5-5.

Then Pless broke Voinea, starting a run of eight consecutive games to finish the match.

Pless earned a second-round match against Martin, who is seeded fourth in the tournament. . . .

Mashiska Washington also earned his first ATP Tour victory yesterday, beating Juan Ignacio Chela, 2-6, 6-3, 6-4.

It was Washington's third victory in three days; he needed to win two qualifying matches to earn a spot in the 56-player tournament. . . .

Thirty local youngsters participated in a clinic yesterday sponsored by Mercedes Benz and organized by the Washington Tennis and Education Foundation. The participants also had a chance to talk to tour players Alex Corretja, Nicholas Kiefer, Mark Keil, Marcos Ondruska, Marius Barnard and John-Laffnie de Jager.

Legg Mason Tournament

Where: William H.G. FitzGerald Tennis Center.

When: Through Sunday.

Tickets: Available through TicketMaster, $6-$60.

Today's featured matches: 4 p.m., Mashiska Washington vs. No. 6 Nicolas Kiefer, followed by No. 8 Marat Safin vs. Sebastien Lareau; 7 p.m., No. 1 Yevgeny Kafelnikov vs. Wayne Black followed by Kristian Pless vs. No. 4 Todd Martin.