Susan O'Brien from the Curl Swim Club in Rockville said she has been hearing about the swimming exploits of 13-year old Michelle Griglione for most of the winter season. But it was O'Brien who swam the fastest qualifying time in the 100-yard backstroke trials yesterday.

And last night she swam a 58:22 to beat Griglione in the final at the Region II Short Course Championship Meet at the White Oak Swim Center in Silver Spring.

O'Brien said her trial run earlier in the day gave her confidence for her first-ever meeting with Griglione later. "She's incredible for her age," O'Brien said of her younger rival. "She could do anything she wanted to. Her times are dropping like crazy."

Griglione won the 50-yard freestyle (24.0), qualifying for the senior nationals at Indianapolis on April 6-9. Griglione, from the Northern Virginia Fun and Fitness Club, teamed with Gretchen Wasserstron, Christine Smith and Lisa Farris to take second in the women's 400-yard medley relay, setting a national 13-14 age group record of 3:57.21. The winners from Curl Club consisted of older girls.

O'Brien, a junior at Walter Johnson High School, quit swimming when she was 15, but returned at age 17. "I wanted to take a break," she said. "I didn't take it seriously, I didn't take it with my heart."

Although O'Brien's time was fast enough to qualify for the senior nationals, it wasn't necessary. She qualified in the 100-yard backstroke and the 200-yard backstroke in December.

Ricardo Aldabe of the North Baltimore Aquatic Club won the men's 100-yard backstroke, easily quailifying for the nationals in 51:43, almost two seconds ahead of second-place Dan Veatch from Rockville Montgomery.

The meet, which drew participants from as far away as Pittsburgh and Petersburg, Va., is one of the last chances for the swimmers to qualify for the junior and senior nationals.

Solotar Swim Team led the team competition with 1,585 points, followed by Rockville Montgomery, with 1537. Northern Virginia Fun and Fitness was third with 1,229.

The meet will end today with five events each for men and women.