Just a quick update for you. Priscah Jeptoo, Tirunesh Dibaba and Florence Kiplagat are still in contention in the women's elite race while Tatyana McFadden is set for a course record in the women's wheelchair race. Mo Farah losing ground on the leading pack, the double world champion was about 45 seconds behind the leaders through 10km, which is a tad slower than he would have wanted.

Brendan Foster
BBC Sport athletics commentator

"Mo's running slightly slower than course-record pace. Don't get too excited Mo. It's at halfway where you need to make your decisions."

The elite men are jogging around the Cutty Sark and the crowd along the streets of sunny Greenwich seem to be five to six deep. Unsurprisingly, yells of "Go Mo" dominate as the Briton, looking relaxed, puts one foot in front of another, which is the best way to run, really.

Tanni Grey-Thompson
Six-time London Marathon winner on BBC TV

"That was a fantastic race by Marcel Hug. When he looked over his shoulder in the final sprint it seemed like he was waiting for Dave Weir to come through. It was a great push by Dave, but just not good enough today."

Marcel Hug in front as the leading pack of four steer down The Mall. The bell rings and Weir and Hug push on but the Swiss is hanging on to his lead, Weir can't get near and the Briton must settle for second spot.

Six-time champion David Weir is positioned behind leader Marcel Hug, who has been runner-up in three of the last four London Marathons. The Briton seems primed for a sprint finish and is being encouraged by vociferous supporters as he passes a pleasing-on-the-eye tree-lined road.

Paula Radcliffe
Women's marathon world record holder on BBC TV

"They are running a very good pace in the women's race - the low 2:17s at the moment. Priscah Jeptoo looks the most comfortable in the leading pack, while Tirunesh Dibaba is just watching."

Brendan Foster
BBC Sport athletics commentator

"Mo's decided not to go with the group with [pacemaker] Haile [Gebrselassie]. He's in the second group. It's sensible from Mo. Mo has decided to let the main group go away. Is Mo going to judge it right? Will the leading group slow down? What will he be like at the 20-mile mark?"

Farah swipes a bottle of water like an old pro, a technique he has been practising after missing one drinks station and picking up a rival's bottle at another during last year's race, when he dropped out at halfway.

I'm not sure if you're interested, but there are 23 water stations on the course. One per mile from the three-mile mark. Little, often, and early is the rule to follow.

The thumping beats of Daft Punk are echoing around Blackheath as a number of 'fun' runners are still patiently waiting to cross the start line. In the men's elite race, Mo Farah is not with the leading group of 11, who are accompanying pace setter Haile Gebrselassie, but that was always the plan.

Tiki Gelana, the fastest lady on paper in the field, has dropped off from the leading pack which still includes defending champion Priscah Jeptoo and Tirunesh Dibaba. The women have completed the last six miles at world record pace so it's not surprising some have fallen behind.

Marko Alpner:, external Gebrselassie is a pacemaker. This is just wrong

Dan Baynham:, external I didn't realise before how many people actually ran in the London Marathon, literally am in shock!!

Tom Fordyce
BBC Sport's chief sports writer in London

"Wonderful atmosphere in Blackheath as Mo's journey into the unknown begins. If you want to get an idea of the pace he'll be running, pop down your local track and run a lap in 72 seconds. Then imagine repeating that 100 more times, without a break. Yup."

Around 36,000 people are expected to take part in today's event and heads are currently bobbing over the start line along like popping corn. Energy drink? Check. Comfortable footwear? Check. Big Bird costume? Check. It will take some time for every competitor to cross the start line but we're under way at least.

At the halfway point in the men's wheelchair race, Britain's David Weir is well in contention and leads along with Swiss rival Marcel Hug just ahead of South Africa's Ernst van Dyk and Kota Hokinoue of Japan.

In the women's race, American Tatyana McFadden is the pace setter and is already around 20 seconds ahead of Japan's Wakaka Tsuchida as they cross Tower Bridge and well on course to defend her title.

Mo Farah, shades protecting his eyes from the sun's glare, bounces on the start line like a featherweight boxer. The crowd start their countdown from 10, hearts are beating faster, thump-a-de-dump... three, two, one - and a cast of thousands set off.

Tom Fordyce
BBC Sport's chief sports writer in London

Mo's view as he comes off the elite start with 26.15 miles still to go.

Brendan Foster
BBC Sport athletics commentator

"Looking at the field that has been assembled, I think Mo has chosen an Everest to climb. Can he do it? We will have to wait and see."

Mo Farah's former PE teacher Alan Watkinson on BBC TV: "I first met Mo when he was a callow youth of 14. I always told people to look out for him as one to watch and I was right.

"If anyone can do it against this sort of field, he can. We doubted him in the past and he has proved us wrong and he will give it his best shot."

Tsegaye Kebede (Ethiopia) PB: 2:04.38 - "I am in great shape. There is no way I am not winning again," says the 2010 & 2013 winner, who also finished fifth in 2011 and third in 2012.

Wilson Kipsang (Kenya) PB: 2:03.23 - "If the weather is good, with a strong field, a world record is very possible," says current world record holder Kipsang, who does not consider Mo Farah to be a big threat.

Geoffrey Mutai (Kenya) PB: 2:04.15 - Mutai, who ran the fastest ever marathon in 2011 in Boston but on a course not given 'official' time status, was the man who beat Farah in the much talked about New York half-marathon last month.

Stephen Kiprotich (Uganda) PB: 2:07.20 - World and Olympic marathon champion Kiprotich claimed only the second gold in Uganda's history when he won marathon gold in London 2012.

Image source, Getty Images