2:15 p.m. Margaret Okayo has left Catherine Ndereba in the dust of Commonwealth Avenue. She could break the women's course record of 2:21:45, set in 1994 by Uta Pippig. Okayo's personal best is 2:24:21, set in New York last year.

2:10 p.m. Margaret Okayo is making a move, putting about 25 yards between herself and Catherine Ndereba at Mile 25. She is about to enter Kenmore Square.

2:05 p.m. Margaret Okayo and Catherine Ndereba are still running stride for stride near Kenmore Square.

2:02 p.m. Rodgers Rop, 26, of Kenya, has won the 106th running of the Boston Marathon in an unofficial time of 2:09:02. His previous personal best was 2:09:51, set in New York last year. Christopher Cheboiboch, also of Kenya, finished second.

2:00 p.m. The men finished 25 miles in 2:02:53. Rodgers Rop is in Kenmore Square.

1:59 p.m. The women, Margaret Okayo and Catherine Ndereba, are on a course record pace as they run through Cleveland Circle in Brookline. They ran 22 miles in 1:58:28. The course record for women is 2:21:45.

1:57 p.m. Rodgers Rop is increasing his lead to about 20 yards over Cheboibach. Rop keeps turning around and gesturing to his countryman to catch up to him. They are in Brookline.

1:55 p.m. The men are at mile 23. Rodgers Rop has opened a lead over Cheboibach. Catherine Ndereba moved up and is running almost neck-and-neck with Margaret Okayo.

1:51 p.m. The women are on Heartbreak Hill. The two leaders are unchanged.

1:44 p.m. Two Kenyans continue to lead the women's race: Margaret Okayo and defending champ Catherine Ndereba.

1:42 p.m. Some men's runners have dropped back; Rodgers Rop of Kenya is now leading countryman Christopher Cheboiboch by a few paces. The defending champ, Lee Bong Ju, is 16 seconds behind the leaders.

1:37 p.m. The men's leaders have narrowed to a handful of runners, including Rodgers Rop, Fred Kiprop, and Christopher Cheboiboch.

1:33 p.m. The women's race has turned into a two-woman duel between Margaret Okayo and Catherine Ndereba, both of Kenya. They are on a course record pace of 2:21:09. The men's race, also led by Kenyans Rodgers Rop and Joshua Chelang'a, have just passed Newton City Hall near the 19-mile mark.

1:30 p.m. Edith Hunkeler, 28, of Switzerland, has just won the women's wheelchair race in an unofficial time of 1:45:57, about 8 minutes faster than last year.

1:25 p.m. The women have run 16 miles in 1:25:45. Margaret Okayo of Kenya has taken a slight lead, with fellow Kenyan Catherine Ndereba and Sun Yingjie of China close behind. They are running at a 2-hour, 24-minute pace, not a world record time.

1:20 p.m. Rodgers Rop, Fred Kiprop, and Joshua Chelang'a -- all of Kenya -- are leading the pack of men's elite runners as they pass through the Wellesley Hills. They just ran a 4:38 mile, the fastest of the course thus far.

1:15 p.m. Edith Hunkeler of Switzerland is still leading the women's wheelchair race.

1:13 p.m. In the women's race, Sun Yingjie of China, Catherine Ndereba of Kenya, and Elfenesh Alemu of Ethiopia, and Margaret Okayo of Kenya are close together and trading places in the top three spots.

1:10 p.m. The men's elite runners are still closely clustered in Wellesley, with less than half of the race left.

1:07 p.m. Ernst F. Van Dyk, 28, of South Africa has repeated as winner of the men's wheelchair race in an unofficial time of 1:23:19, close to two minutes faster than last year.

1:05 p.m. Edith Hunkeler is leading the women's wheelchair race at Mile 19 by 250 meters. Her second-place time last year was 1:53:58.

1:03 p.m. Ernst F. Van Dyk, the men's wheelchair leader, is in Brookline, about a mile and a half from the finish line. His winning time last year was 1:25:12.

12:55 p.m. The leader in the women's wheelchair race is Edith Hunkeler of Switzerland, who finished second to Louise Sauvage last year. In the men's wheelchair race, Ernst F. Van Dyk is on a near-world record pace.

12:50 p.m. The male runners are entering Natick Center, with Elly Rono of NC still in the lead. Defending women's champion Catherine Ndereba is leading the women. Her Kenyan countrywoman, Margaret Okayo -- winner of the NYC Marathon -- is also in the lead pack of female runners.

12:43 p.m. The men have run the last 2 miles of the race in under 5 minutes each. The elite runners are clustered together at the front and are at Speen Street in Natick. Ernst F. Van Dyk has passed the 18-mile mark in 43 minutes, 50 seconds.

12:35 p.m. Ernst F. Van Dyk of South Africa, the defending champ, has a large lead in the wheelchair race.

12:25 p.m. Elly K. Rono of NC is leading the men's race, with Lee Bong Ju right behind.

12:22 p.m. Lori Stich-Zimmerman of Texas is the lead women's runner, on pace for a 2-hour, 24-minute Marathon. Catherine Ndereba is close behind.

12:15 p.m. Ernst F. Van Dyk, the men's wheelchair leader, passed the 10-mile mark in 30 minutes, 40 seconds.

12:10 p.m. Defending men's champion Lee Bong Ju is in front as the elite runners enter Ashland.

12:06 p.m. Defending wheelchair champion Ernst F. Van Dyk of South Africa is in the lead.

12:05 p.m. Although the rain showers have stopped, it is 53 degrees and overcast in Hopkinton.

Noon Led by returning champions Catherine Ndereba of Kenya and Lee Bong Ju of Korea, the 16,638 official runners -- and countless unofficial runners -- in this year's Boston Marathon have left the starting line in Hopkinton.

11:45 a.m. The wheelchair racers have started the 106th Boston Marathon.

11:30 a.m. The wheelchair racers are queuing up at the starting line in Hopkinton.