Ethiopian athletes may have obliterated their opponents in Monday's Boston marathon, the opener in this season's World Marathon Majors (WMM), but Kenyans are strong favourites to win Sunday's London race.
Kenyan men have won seven out of the last 16 London competitions and Kenyan women six, while Ethiopians have won just twice in each category.
Reigning WMM champions Eliud Kipchoge and Mary Keitany will lead a strong Kenyan contingent that also includes former London marathon winners, Wilson Kipsang and Priscah Jeptoo.
With places in the Rio Olympics team up for grabs, the Kenyans are eager to put in their best performances.
A new anti-doping law, due to be passed before May 2, is aimed at saving Kenya's runners from a threatened Olympics ban after a spate of positive drug tests among athletes.
Men's champion Kipchoge, 31, says his goal is Olympic selection not breaking the course record of 2:04:00 set in 2014 by fellow Kenyan Wilson Kipsang.
"I always love the challenge of competing in the big city marathons," Kipchoge told AFP before departing for the British capital on Monday night.
"But I cannot say I will be going for the course title. Marathon running is a team event," said Kipchoge, who is set to face Kipsang and world record holder, Dennis Kimetto, in a repeat of the 2015 London marathon.
Kenyan-based Italian coach Renato Canova has singled out Kipchoge, a former world 5,000 metre champion and Olympic silver medallist, as the runner to watch this season.
"Kipchoge is head and shoulders above all the Kenyan marathon runners and he is a very strong contender to win the Olympic gold medal in Rio," said the Iten, Kenya, based Canova, who has coached several Kenyan marathon runners over the past five years.
So focused on the Olympics is Kipchoge that he has not run a marathon event since Berlin in September, when a broken shoe denied him a world record. Kipchoge finished the race in a personal-best time of 2:04.00 but well outside the world record of 2:02.57.
Two-time champion Kipsang, 34, has not ruled himself out of contention for the London title.
"The performance on the day will depend on how well one has prepared himself for the race," said the 2012 Olympic bronze medallist, after his final 25 kilometre (16 mile) run in Iten at the weekend.
"I have practised my finishing very well and I'm ready for the London marathon and a place in the team for the Olympics," said Kipsang.
Keitany finished runner-up to Ethiopian Tigist Tufa in the women's race last year, but the 34-year-old mother of two has the fastest time on the start list for London.
Buoyed by a solid performance during her New York marathon title defence last November -- when she relegated Tufa to third place -- Keitany believes she is strongly-placed to win the race and become only the fourth woman runner to win the London marathon three times.
"I have won London twice and the atmosphere is very welcoming. I feel very much at home competing there" said Keitany who was, however, disappointed when a hip injury forced her training partner Gladys Cherono to withdraw from the race.
Cherono, the Berlin marathon champion and last year's fastest marathoner had been expected to make her London marathon debut on Sunday.
Fellow Kenyan and current world half marathon record holder Florence Kiplagat will also be competing in what will be her fifth London marathon. She finished second in 2014.
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