With returning winners and talent-packed fields, Jack Houghton identifies the value bets in this year's London Marathon and highlights some in-play pointers...
"Stanley Biwott is the best value at around 5/1. He was second here in 2014, won New York in November, and was only just run out of it in a sprint finish in the RAK Half Marathon in February."
The London Marathon
Sunday, 24 April
Live on BBC2 from 08:30 & BBC1 from 10:30
Women's Race Preview - 09:15 Start
Mary Keitany, at around 5/4, will be hard to beat as she tries to win her third London Marathon, but she faces a competitive field. Surprisingly beaten into second last year, Keitany is the fastest marathoner in the race and showed she retains her best form by regaining her New York title last November. Not seen since that victory, though, her current state of fitness is an unknown.
Tigist Tufa is the much-vaunted second-favourite (around 100/30) having won the race last year. It was a very slow pace on that occasion, however, and her personal best of 2.21.52 from Shanghai doesn't read well when there are four others in the field who have gone sub-2.20, and a further three with faster times to their names than Tufa. She showed no better than average form in the World Championships last summer, and again at the New York Marathon in November and so, at the odds, she's one to avoid.
Mergia, Kiplagat, Dibaba, Jeptoo, Tadese and Sumgong complete a field of possible winners and it's hard to split them. All have big-city marathon honours and all have posted personal bests that would win an average London Marathon. Most of their best form, though, came before 2015, with the exception of Mare Dibaba. Unrelated to the Dibabas of track fame, she has nonetheless shown a lot of potential and, at only 26, is the most likely in this field to show any improvement. Her run in a half-marathon in Houston in January showed she is in form and if she is able to run near her 2.19.52 personal best (a time, unusually, that she has run on two separate occasions), then she will be hard to beat.
Verdict: Mary Keitany might be pushed close by Mare Dibaba
Men's Race Preview - 10:00 Start
Defending champion Eliud Kipchoge is the rightful favourite at around 7/4. He beat previous two-time winner Wilson Kipsang in a tight finish last year and has since gone on to win Berlin in a personal best of 2.04. That made it five marathon wins out of six and he'll be looking to beat Kipsang's course record of 2.04.29 on Sunday, a time he narrowly missed last year. One concern for those taking the odds on the favourite is that he hasn't raced since Berlin, last September. That doesn't preclude a victory - marathons are won by training, not racing - but it does mean we have to take his form on trust.
Wilson Kipsang is the most successful marathoner in this field and knows London better than any of them. There is a lingering doubt, though, that, at 34, his best days are behind him. He hasn't won a marathon since 2014, lost both his London and New York titles in 2015 to runners he will face on Sunday, and ran an awful race in the RAK Half Marathon in February. He's got the class, without doubt, but 3/1 looks on the short side.
Dennis Kimetto stunned the world with his 2:02:57 in Berlin in 2014, but is another who has disappointed since. He couldn't stay with the front two in the closing miles here last year, and dropped out of the Fukuoka Marathon in December. If recovering his best form, the 13/2 will look generous, but on balance he's probably one to avoid.
Stanley Biwott is the best value at around 5/1. He was second here in 2014, won New York in November, and was only just run out of it in a sprint finish in the RAK Half Marathon in February. He seems to be on an upwards curve and makes more appeal at the odds than the favourite, Kipchoge.
Of interest at bigger odds (around 20/1) is Ghirmay Ghebreslassie of Eritrea. He was a surprise winner of the World Championships in Beijing last year, and although his personal best is a long-way short of what will be required to win London, he undoubtedely has the potential to improve on that. He has missed a few planned appearances so far this year, though.
Verdict: Eliud Kipchoge is the most likely winner; Stanley Biwott is the best value.
The course is flat. Actually, it's slightly down-hill. This is crucial. There are no harder sections to radically change things: it's all about pacing.
The start in Greenwich means little. Just don't be confused should anyone re-attempt Dave Hellard's feat of 2013.
Expect a fast start, with pacemakers leading the way. Unless anything dramatic happens at this stage, there will be no conclusions to be drawn about the likely winner.
Rounding Cutty Sark, just before mile Seven, the winner will be in an elite group of no more than about a dozen runners. If your fancy is absent, they won't win. Elite marathons nowadays consist of those who can operate at world-record pace, and those who are five minutes over that. The latter have their own pacing strategies and will be absent from the front early on. This will include all of the European representatives.
Crossing Tower Bridge, expect commentators to say that a world-record is on the cards. Beware Kenenisa Bekele, though. He is arguably the greatest track runner of all time, transitioned well to road running with a win in the 2014 Paris Marathon, but only posted a mediocre time in doing so and was injured all of last year. He will probably be going well at this, the half-way stage, but expect him to falter later.
Docklands, between miles 15 and 20, can often be the key to the race. A mid-race move can often break less buccaneering competitors. Be prepared to back those making a play for race victory.
The final stages - running down the Embankment towards Big Ben, passing the Houses of Parliament and turning into The Mall - have seen plenty of close finishes over the years. Try and ignore the commentators' obsession with which athlete "has the best track speed," though. It is a factor, but far more telling is how comfortable a runner looks: plenty of speed-merchants have been out-sprinted at this stage by opponents who have pushed them to their endurance limits beforehand.
Betfair launches bigger and better 'Back Yourself' site for 2016 London Marathon
We have re-launched our successful campaign Back Yourself to mark the 2016 London Marathon, offering runners the chance to win money for their charity by betting on themselves to hit their target time. The site will be open to all participants from Wednesday (April 20) until Saturday (April 23).