NAIROBI, March 28 (Xinhua) -- London marathon champion Daniel Wanjiru of Kenya has warned his rivals not to underestimate his ability ahead of his title defense on April 22.

Wanjiru will be among a horde of elite runners who will be eyeing the big cheque with organizers putting 100,000 U.S. dollars up for any runner in the men's race who runs a sub-2:05:00 time, and to any runner who bests 2:18:00 in the women's race. This is alongside the 55,000 U.S. dollars for the winner, irrespective of time taken.

"No one expected me to win in last year's marathon. But I believed and I will believe again. Don't underestimate me," said Wanjiru on Wednesday from Eldoret.

The 25-year-old, who was eighth at the World Championships last year (clocking 2:12:16) faces one of the strongest groups of elite runners in London including Olympic champion Eliud Kipchoge, last year's runner-up Kenenisa Bekele and Mo Farah.

"Today I enjoyed my training. Now I'm focused, determined and motivated than ever. I look forward to another surprise win," he added.

Other Kenyans lining up in London are Samuel Chelanga, who now runs for the USA, Abel Kirui, a two-time world marathon champion, Lawrence Cherono, Bedan Karoki (who was third last year), and Stanley Biwott, a former New York and Tokyo marathon winner.

But the focus has been beamed on Kipchoge, Bekele, and Farah who are viewed as the best long-distance runners of their generation.

The trio (Bekele, Farah and Kipchoge) have a combined total of eight Olympic gold medals and 12 World Championship golds between them.

Since making his debut in Paris in 2014 in 2:05:04, Bekele has only completed four more marathons.

In addition to his personal best in Berlin last September, he was fourth in Chicago in 2014 (2:05:51) and third in London in 2016 (2:06:36). He has twice failed to finish in Dubai.

Farah, 34, is the most decorated, with four Olympic gold medals and six World Championship victories over 5,000m and 10,000m. Bekele, 35, is the 5,000m (12:37:35) and 10,000m world record holder (26:17:53), the second fastest marathon runner in history (2:03:03) and the owner of three Olympic and five World Championship gold medals.

But it is Kipchoge, 34, who has the greatest marathon pedigree. The Kenyan, two-time London Marathon champion, is widely seen as the greatest marathon runner of his generation.

He has run an unratified marathon time of 2:00:25 and is the reigning Berlin and Olympic marathon champion.