After 2,057 miles of the 3,117-mile McDonald's Race Across America that will end at the Washington Monument Monday, no more than 10 miles separate the top three men bicyclists and only 48 minutes separate the leading two women.

A total of 35 riders started the race last Saturday morning in San Francisco, and now, after 145 hours of almost nonstop riding, 22 are left.

Michael Secrest of Flint, Mich., took the lead 1,046 miles into the race in Dinosaur, Colo., Tuesday morning and hasn't succumbed to his pace of more than 260 miles a day on fewer than two hours of sleep a night.

Secrest, 34, a professional cyclist who finished second in this race in 1985 and third in 1983, passed through Sedalia, Mo., at 3:48 p.m. yesterday, leading one of the more tightly packed fields in the race's six-year history.

Trailing Secrest by just 27 minutes is Bobby Forney, a 29-year-old cartographer from Evergreen, Colo. And Michael Trail, 43, of Colville, Wash., is just seven miles behind Forney.

"It's not usually this close," said Richard DiBernardis, headquarters director in Tucson. "Last year at this point, they were about 100-150 miles apart. We usually say that whoever crosses the Mississippi River first will win, but not this time."

Casey Patterson, 43, of Topanga, Calif., has led the four women racers since the start. She passed through Phillipsburg, Kan., 1,668 miles from San Francisco, in 16th place overall, at 12:58 p.m. yesterday.

Cheryl Marek, 31, of Seattle is 48 minutes behind Patterson in 18th place and Marie Costellic, 28, of Mount Pleasant, Pa., is 160 miles behind Marek and just 10 minutes ahead of Cherie Moore, 23, of Westerville, Ohio. Moore was in third place among the women until 2:40 p.m. Thursday, when Costellic overtook her in Cope, Colo.

What makes the leaders' proximity to each other more notable is the course's relative difficulty compared with last year's flat, southern route from Huntington Beach, Calif., to Atlantic City. Avoiding any real mountains, Pete Pensyers won last year in 8 days 9 hours 47 minutes. Elaine Mariel won the women's race in 10 days 2 hours 4 minutes.

After pedaling across California and Nevada, the cyclists climbed to 11,300 feet to cross the Rocky Mountains and will again face a steep ascent when they reach the Appalachians, before the final run into Washington.

Originally, it was estimated the men's winner would arrive in D.C. at about 11 a.m. Monday, but officials now are saying it may be later. At an average speed of 14.1 mph, Secrest is 2 mph slower than Pensyers' pace.

Using projections that are also subject to change, the women are expected to complete the race late Tuesday afternoon.