Lisa Larsen Weidenbach was one of the most surprised finishers yesterday in the Nike Cherry Blossom 10-Mile run in West Potomac Park.

"I'm a little embarrassed after telling everybody how poorly I expected to finish," she said after breaking the women's course record and winning the women's division of the 13th annual race in 53 minutes 30 seconds. "I was tired after last week, (when she set a U.S. record for 30 kilometers at Albany, N.Y.) and I didn't think I had anything left."

The previous women's course record (53:46) was set by Eleanor Simonsick of Baltimore in 1983.

The men's course record and world record for 10 miles also could have been broken had not the pace been so slow for the first half of the race. But the early pace helped Simeon Kigen earn his second consecutive Nike Cherry Blossom victory in 46:24, 61 seconds faster than last year's time.

Each winner received a check for $3,000. Jacqueline Gareau (53:56) of Canada and Sosthenes Bitok (46:39) of Tarrytown, N.Y., earned $1,500 apiece for second-place finishes.

While Kigen was 10 seconds off the record, hundreds of the 4,000 finishers ran personal bests and several U.S. single-age records were established. The weather was near perfect, with temperatures in the low 50s and moderate wind. And the course, which winds through blooming cherry blossoms in West and East Potomac parks, was flat and fast as usual.

Larsen Weidenbach, 23, from Marblehead, Mass., made the best of it. After trailing Gail Kingma of Seattle (third place in 54:01) for eight miles, Larsen Weidenbach surged into the lead and was never challenged. Last year, she kicked at the same point, but Rosa Mota caught up with 400 meters left to defeat Larsen Weidenbach by one second.

"Once I passed Gail, I didn't want that to happen again," said Larsen Weidenbach, whose time was only 11 seconds off the U.S. record for 10 miles. Gareau, 32, remained 20 meters behind for virtually the entire race and finished in 53:56.

The men's race was more tactical. Most of the 15 runners in the front pack at the mile knew Kigen would be patient until the last few miles. Last year he waited until the last mile to unleash his kick, and his 46:14 last week (one second off the world record set by Greg Meyer here in 1983) put him far up on the competition.

Before the pack had thinned by the five-mile mark, nobody was willing to run faster than a 4:41 per mile pace. "I was a little upset that the guys weren't committed to run very fast until four miles," said Jon Sinclair, 27, from Fort Collins, Colo., who placed third in 46:45. "The pace seemed real lethargic to me."

When the leaders reached the midway point, the top four finishers -- two Kenyans (Kigen and Bitok) and two Americans (Sinclair and Thom Hunt) -- broke away as a pack. Sinclair tried three times to surge ahead but each time, the other three runners quickly caught him. Sinclair made his last surge at eight miles, and Hunt, 26, of Eugene, Ore., faded into fourth, where he finished in 46:57.

Kigen, 23, darted into the lead 400 meters later and Sinclair and Bitok moved in directly behind. Another 400 meters later, Bitok dropped from the pace. Sinclair held on, but was straining while Kigen was relaxed. Less than 50 meters later, Kigen pulled away from Sinclair, running the ninth mile in 4:28.

"I was feeling okay at nine miles," said Kigen, a University of Colorado student. "I knew I could outkick either of them (Sinclair and Bitok) if I could stay with them."

Kigen ran away with the race with a 4:24 last mile while Bitok and Sinclair battled down the stretch for second. With 150 meters remaining, Bitok sprinted past Sinclair and opened a six-second margin for second place.

Barry Brown, 40, of Gainesville, Fla., became the fastest American master (age 40 and older) over 10 miles with a 49:46 effort, 31st place overall.

Eddie Benham, 77, of Ocean City, Md., earned a U.S. and world single-age record with a 74:10, seven minutes off the previous record. Percy Perry, 81, of Jersey City, N.J., set a U.S. and world single-age record for 10 miles at 96:22. He was the oldest finisher in the first race in 1973 as well as in this year's race.

Marianne Dickerson, who was favored among the women, was not able to compete after she became ill Saturday with a temperature of 104 and a stomach virus.