"I thought this was my day," said Bea Marie Altieri at the conclusion of the Marine Corps Marathon yesterday. "But all of a sudden it wasn't."

After leading the women's division for nearly 23 miles, Altieri relinquished the top spot to 1997 winner Donna Moore, then struggled to the finish line as the runner-up in 2 hours 56 minutes 48 seconds. Moore, 39, won her second Marine Corps Marathon in 2:51:53.

"My legs felt so heavy the last few miles," Altieri said. "I felt like one of those Flintstones characters: My legs were spinning, but they weren't going anywhere."

Altieri, 33, took the lead early, and led by two minutes at 10 miles; she passed halfway in 1:21:20. "I felt great at that point," she said. "My plan was to be there at 1:23:00, so I didn't think I was going too fast." By 16 miles, Altieri was running among the top 50 men; she led Moore by almost four minutes.

Altieri's coach, Tony Basile, offered his support there, then ran across Memorial Bridge to wait anxiously at the finish. Altieri appeared to have the race sewed up, and Basile was confident she would exceed her goal of 2:50, the qualifying mark for the Olympic trials marathon. Altieri ran her personal-best marathon time of 2:50:01 in 1996.

"She's been doing lots of long track work lately," Basile said. "She ran marathon pace in a training run to win the [D.C. Road Runners] 20-miler three weeks ago."

But the marathon is 6.2 miles longer, and in that interval, Altieri fell apart. "I was shocked when I saw her," Moore said. "I was like, 'Wow, there's Bea.' I knew no one was behind me."

Moore passed Altieri in a rush, and offered encouragement to her clearly vanquished competitor.

Altieri had gone from running miles in an average of 6:30 to more than 8:00. "I hit a huge wall out there," she said. "I was tempted to drop out at 24. It's hard when you've got a goal, and you know you're not going to get it.

"I tried. I gave it my all. I won't try again."

Moore maintained a steady pace throughout the race. "I never hit the wall," she said, "and that's an amazing thing for me, because I always hit the wall. I got tired at the end, but getting tired and hitting the wall are two different things."

Christie Ireland, 28, of Burke, finished third in 2:57:58. Like Moore, Ireland ran conservatively, and moved up steadily throughout the race. "I wasn't worried about anyone else," she said. "This was my first marathon and I had to be careful."

Ireland, who ran track and cross-country at Georgetown before graduating in 1993, was among the spectators last year, and vowed to play a bigger role this year. "It was the coolest thing running past the crowds," she said. "People were amazing."