Kenya's Felix Limo outsprinted countryman and 2005 race winner Martin Lel on The Mall to win a dramatic men's event at the London Marathon.
The pair pulled clear of a group that included Haile Gebrselassie in the final three miles of the race.
Earlier American Deena Kastor became only the eighth woman to run under 2hrs 20mins to clinch the women's race.
David Weir topped the men's wheelchair field, while Francesca Porcellato beat Britain's Shelly Woods in the women's.
1206: The BBC has just caught up with a runner called Guy, who has got to be nuts! He's running his seventh marathon in as many days having started his first epic race in Utrecht a week ago.
1202: A host of elite male runners are coming over the finishing line thick and fast with a combination of relief, elation and exhaustion etched all over their faces. There are thousands of runners from the age of 18 to 80 still out on the course.
1158: Pete Reilly, in his first marathon, clocks a time of 2:14.30 - the top British finisher in the men's field.
1154: An exhausted Gebrselassie comes across the line well off the pace. He looked to have timed his race perfectly until the dying moments and had to make do with ninth.
1152: Limo puts in a sprint as the pair turn into the final straight. Lel looks to go with him but he can't quite pull it off and Limo wins in a time of 2:06.39 - his fastest ever time. Ramaala takes third for an African one-two-three.
1150: Lel decides with less than 600 metres remaining the time has come to up the tempo but he can't quite shake off Limo for now.
1149: The 26th running of the men's London Marathon could well be set for a sprint finish unless one of the Kenyans opts to put in an attack soon.
1146: Limo and Lel, who has not run a marathon since winning in London a year ago, are matching each other stride for stride in the dying moments of the race. Ramaala, though, is still within sight of the leaders although not close enough to bother them for the victory.
1144: There's no more than about six minutes left of the men's race, and the victory looks set to come between Lel and Limo, the Chicago Marathon winner who is competing in the London Marathon for the first time.
1141: Felix Limo seemingly comes from nowhere to catch Lel as the two take up the lead along Embankment.
1138: Lel puts in a massive injection of pace with three miles left. It blows away the likes of Gebrselassie. Only Rop and Ramaala can keep a semblance of pace with him...for now. Lel, last year's winner, looks in good shape for a repeat.
1136: Lel and Rogers Rop, the Kenyan duo, bid to break clear of the rest of the leaders in the men's race. It stretches out the rest before they regroup... but there's still a lot of tactical running going on out there.
1133: Back at the men's elite race, the pace has slowed dramatically and the world record of Paul Tergat is now out of consideration. There are seven runners, though, still in contention for victory.
1129: Shelly Woods crosses the line for an impressive second place in the women's wheelchair race for the 19-year-old.
1125: Yamauchi is the first Briton to cross the finishing line in the women's race. She finishes sixth to become the second quickest British runner of all time (slower only than Paula Radcliffe). She is just over the 2:25 mark.
1124: Porcellato flies over the line at the end of the women's wheelchair race to become the first athlete to win the London Marathon for the fourth straight year.
1122: Petrova clocks a personal best for second in the women's race, clawing back Chepkemei in the latter stages. The Kenyan, watched by her mother, has to make do with the bronze medal. Berhane Adhere seals fourth ahead of the second Russian in the race Galina Bogomolova.
1119: Kastor turns into the mall to applause from the drenched crowd and becomes only the eighth woman to run a sub-2:20 marathon.
1116: Fabiano Joseph, one of the men's pacemakers, has bizarrely broken clear at the front of the field and now holds a six-second advantage over the chasing pack. None of the main contenders, though, look particularly bothered.
1113: There's only two miles to go in the women's race and Kastor, the Olympic bronze medallist, looks destined to take the victory.
1110: Porcellato is well on course for a comfortable win for Italy in the women's wheelchair race. She has a three-minute lead on closest rival Woods.
1107: The men's field is beginning to split after 26km. Gebreselassie, Lel and Ramaala, however, are among the seven runners in the leading group. They're still on for world-record pace.
1105: Kastor holds a one-minute lead after 35km, with Kenyan Chepkemei in second and an all-Russian battle for third between Lyudmila Petrova and Galina Bogomolova. Britain's Yamauchi is still sixth.
1100: Kastor has just one pacemaker with her now after dropping training partner Mike McKeeman. She looks sprightly on the two-hour mark despite her earlier tumble.
1057: There's drama at the head of the women's race when Kastor clatters into a table while trying to take a drink. She appears to damage her wrist a little and briefly checks it before refocusing on her bid for victory.
1054: David Weir ensures at least one British winner in the London Marathon as he crosses the line in front in the men's wheelchair race. He raises his arms in celebration after defying pre-race favourites Saul Mendoza and Ernst van Dyk to break the course record.
1052: Interestingly at the halfway point, the men clock a time of 62 minutes and 33 seconds - that's half-a-minute quicker than Paul Tergat's world-record pace. The lead group has now dropped to just nine runners because of the frenetic speed. One man looking unfazed by it is Gebrselassie.
1047: Just after the hour mark, the elite men reach for their designated drinks. Gebrselassie somewhat generously shares out his with some of his rivals. Much further back the field, there are some smiley faces at Cutty Sark. It remains to be seen whether they will grinning in quite the same way after 26 miles!
1044: Yamauchi's looking in reasonable shape for Britain in the women's race. The former Foreign Office diplomat, who once acted as an interpreter for Baroness Thatcher, is lying sixth at the moment and briefly shakes out her arms to give them a rest not long after the 30km mark.
1038: A shout of "come on girl" rings out on the course as Kastor continues to build her lead and looking in fine fettle. She looks good at the minute for 2hr19min pace. Her pacemakers are setting a near-perfect tempo for her to the 30km mark.
1033: There's a strong African make-up in the leading group in the men's race, among them Ethiopian duo Gebrselassie and Abiyote Guta, Tanzanian Fabiano Joseph and a host of Kenyans, including Paul Kimugul, Felix Limo, Evans Rutto and Lel. They're setting a hefty pace and look unfazed 51 minutes in.
1026: Kastor moves into the lead outright in the women's race with the two pacemakers still going with her. For now, though, Chepkemei cannot keep pace.
1020: Porcellato has pulled out a good 30 metres on the 19-year-old Woods at Tower Bridge in the women's wheelchair race as she goes for her fourth consecutive London marathon win.
1014: Olympic champion Stefano Baldini has been blown away early on and is about 100 metres behind a lead group of almost a dozen runners, including last year's winner Martin Lel and Gebrselassie. Gebrselassie remonstrates with two female spectators who get out on the course but quickly dart back onto the pavement after he "has a word".
1011: There's a few latecomers still making their way over the startline. A 14-man green dragon, running for Juvenile Diabetes, has just been spotted on the course.
1006: Kosgei is dropped in dramatic fashion just before Kastor and Chepkemei cross Tower Bridge - that's the halfway mark of the women's race. They're operating in 2 hour 20 minute pace, which would break both runners' personal bests.
1000: Mara Yamauchi is looking impressive for Britain in the women's elite race. She is part of the chasing group to the leaders - a little more than a minute off the pace - but looks in good shape. That lead group, however, could drop down to just two runners with Kosgei struggling now.
0955: Britain's Shelly Woods is in contention in the women's wheelchair race but has her work cut out in a head to head with Italian Francesca Porcellato.
0950: Among the better costumes already spotted are Bill and Ben the Flower Pot Men, a dalek and a knight in shining armour dragging a massive dragon. Further up the field, Kosgei, Chepkemei and Kastor still enjoy a solid lead. Kastor, who dismissed her favourite tag, will certainly be boosted by the fact her training partner Mike McKeeman is one of the two leading pacemakers. Meanwhile, in the men's wheelchair race Mendoza and Britain's David Weir are battling it out for the lead.
0945: Seb Coe gets the men's elite race under way, with those leading athletes closely followed by the masses.
0940: As a side event to the main action, the mini-marathons are also taking place in London, with young athletes from across the country competing.
0934: One of the three leaders in the women's race, Kosgei, takes a tumble at the water station. She doesn't look hurt, although that remains to be seen, and quickly rejoins the other two front-runners. That leading trio then reaches Cutty Sark with a hefty lead - 36 seconds - over their chasers.
0932: Distressingly Jade Goody, of Big Brother fame, has just revealed to Sue Barker the most she has run is half-an-hour on a treadmill in training. She revealed her training regime involved eating Chinese and Indian food as well as boozing. Her biggest concern is that her toenails will fall off!
0925: The wheelchair athletes head out on the course. Mexico's Saul Mendoza is going for three wins in a row but is up against South African world-record holder Ernst van Dyk.
0922: The BBC has just caught up with bride-to-be Katie Austin and her husband-to-be Gordon Fryer, who are both dressed in their full wedding gear. Katie's dad Bob is running with them to give her away midway through the race. They've asked friends and family not to buy them wedding presents but to donate to Hel the Hospices. The pair have so far raised £12,000.
0914: There are just three women runners at the front of the field now - Kastor, Chepkemei and Salina Kosgei, along with their two male pacemakers. Chepkemei has not won a marathon since 2001 but finished last year's race in London in third.
0905: Two male pacemakers are dragging the elite women athletes along. Kastor and Susan Chepkemei are among the athletes in a leading group of about 10. Interestingly, Chepkemei is being watched by her mother, who has come from Kenya to see her daughter compete.
0900: The women's race gets under way in the wet conditions under the watchful eye of starter Seb Coe.
0856: A host of celebrities are competing today, among them the Olympic trio of Matthew Pinsent, Sir Steve Redgrave and James Cracknell, as well as chef Gordon Ramsay and former Big Brother contestant Jade Goody. Redgrave is bidding to break the world record of £1.25m for individual fundraising for an event.
0851: There will be the sound of wedding bells on Sunday, with Katie Austin and Gordon Fryer, from Romsey, Hampshire, planning to marry at the halfway point. They will tie the knot in a half-hour ceremony in the Bridge Master's dining room at Tower Bridge before finishing the race.
0847: There are a host of bizarre competitors in action on Sunday. Perhaps the most obscure is Lloyd Scott, who completed the 2002 event in a deep sea diving suit and will this year wear an eight-foot steel dragon costume to raise money for children with leukaemia.
0840: It's a damp and dreary day in London but that's failed to deter some 35,000 athletes from competing in the 26.2-mile London Marathon. The women's race gets going at 0900 BST, the wheelchair race at 0925 and the men's and masses get under way at 0945.