Argentine tennis star Guillermo Canas promises to fight a two-year suspension by the ATP for testing positive for a diuretic.

Canas, ranked No. 10 and a French Open quarterfinalist this year, said he never knowingly ingested a banned substance. He plans to appeal to the Court of Arbitration for Sport in Switzerland.

"I know I'm innocent," Canas told the Argentine newspaper La Nacion. "My career isn't going to end, that's for sure."

Canas, winner of six ATP tour events in his career, tested positive in February at the Mexican Open. Diuretics increase urine production and are used to treat patients with renal problems. They also are misused to mask the presence of other banned substances such as steroids. . . .

Lleyton Hewitt quit during his opening match at the Rogers Cup in Montreal, weakened by a stomach ailment that forced him to retire for only the second time in his singles career. The second-seeded Australian was trailing French qualifier Florent Serra 4-3 at the time in the ATP Masters Series tournament.

Meantime, Paul-Henri Mathieu's 14th ace finished off Legg Mason Classic winner Andy Roddick, 7-5, 6-3.

* COLLEGE BASKETBALL: George Washington senior Pops Mensah-Bonsu, Georgetown senior Brandon Bowman and Maryland senior Nik Caner-Medley are among 50 preseason candidates for the Wooden Award, given annually to the nation's best player. . . .

J.J. Redick of Duke hit six three-pointers and scored 22 points to lead the United States (4-0) to a 113-78 victory over Nigeria in the preliminary round of the men's under 21 world championships in Mar del Plata, Argentina.

* COLLEGE FOOTBALL: Maryland reserve running back T.D. Callahan suffered a significant sprain to his left knee in yesterday's practice and will have an MRI exam today. The walk-on was fifth on the preseason depth chart at one of Maryland's shakiest positions.

* GOLF: Brendan DeJonge, a Nationwide Tour player, shot 5-under-par 67 for a two-day total of 136 to win the sixth annual Holden Cup at Belle Haven Country Club. DeJonge, who received a $6,000 first prize, tied the course record set by Rob Stock in last year's event.

First-round leader Dirk Schultz, PGA professional at Black Rock Golf Club, who along with amateur Ken Lampard won the four-ball competition Monday, tied for second at 143 with three others. The event raised $60,000 for the Susan G. Komen Breast Cancer Research Foundation. . . .

The Washington Metropolitan Golf Association team of Kyle Stough, Jeff Henry, Myles Vlachos and Mitch Van Zandt tied for fourth place with 449 at the 42nd annual Williamson Cup at Bent Creek Country Club in Lititz, Pa. The Washington team led by three strokes after the first round thanks to Stough's 3-under 68. The Golf Association of Ontario (Canada) won the tournament with 440.

* OBITUARIES: Colette Besson, a physical education teacher who scored a big upset to win the 400-meter gold medal at the 1968 Olympics, died of cancer in Paris. She was 59. . . .

Glynn Carlock, who won two Virginia football championships as coach at Graham High School in Bluefield, Va., died Monday night. He was 67.

Carlock died two weeks after he was diagnosed with the rare brain disorder Creutzfeld-Jakob Disease.

-- From News Services

and Staff Reports