Ann Hoefler of Silver Spring filled a big pair of running shoes with a small pair of feet yesterday in the fifth annual Bonne Bell/Chevrolet 10-kilometer road race in West Potomac Park.

The 12-year-old White Oak Junior High School seventh-grader broke from a pack of four women after four miles and fought off a last-second challenge by Kathleen Hibbert of Rockville to win in 37 minutes 2 seconds.

Hoefler became the youngest to win the race.

Hibbert, 28, finished one second behind in 37:03 in the 6.2-mile event. Anne Densmore (37:21) of Hancock, Md., and Kathy Heckman (37:33) of Richmond placed third and fourth, respectively.

Hoefler eased through the first mile, running in fifth place 50 yards off Densmore's 5:30 pace. Heckman, Diane Miller of Fairfax and Hibbert trailed the 13-year-old Densmore, who held a 20-yard lead for another mile until Heckman and Hibbert drew even with her.

But by 2 1/2 miles, Hoefler caught the lead pack, running beside Hibbert and behind Heckman and Densmore.

Miller had dropped back into fifth place by more than 50 yards. She finished fifth in 38:12.

As the four passed through three miles at Hains Point in 17:58, Hoefler shared the lead with Hibbert on her left and Densmore on her right. Heckman, beginning to struggle, trailed by five yards.

Hoefler made her surge a mile later, as the song "I Am Woman" blared from the van parked on the side of the road. Hibbert moved in behind Hoefler, following by about three yards, with Densmore on her right shoulder.

"I thought they would stay with me," said Hoefler, who set a national 12-and-under 10-kilometer record in the WETA 10-kilometer run (36:23) last November on the same course.

By five miles, Hoefler had established a 15-yard lead, running smoothly and appeared to have clinched the victory. A mile later, though, Hibbert had cut the lead to 10 yards and was closing the gap quickly.

With the finish line in sight less than 100 yards away, Hibbert overtook Hoefler on the sprint but Hoefler outkicked her to break the tape first.

"Did you know it was me who was gaining on you?" asked Hibbert, a good friend of Hoefler.

"I didn't know you were behind me," said Hoefler. "Then I saw you next to me and I started sprinting."

"I feel guilty," joked Hibbert, "I should have been running twice as fast because my legs are twice as long!"

The victory earned Hoefler a trip to Boston for the Bonne Bell series championship on Columbus Day.

The annual event, which has become the largest women's race in the Washington D.C. area, attracted more than 3,200 participants.