Lonyangata pulled clear when his compatriot Stephen Chebogut, who started with the best personal best of the field, cracked with 5.7km left.
The 24-year-old Lonyangata, a winner of the Lisbon and Shanghai marathons, beat his personal best by almost a minute.
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(Reporting by Julien Pretot; Editing by Amlan Chakraborty)
