Kenya's Sammy Wanjiru, the reigning Olympic and London marathon champion, won the Chicago Marathon on Sunday in a course record of 2hrs 5mins 41secs to make a triumphant US debut.

Wanjiru defeated Moroccan runner-up Abderrahim Goumi by 23 seconds with Kenya's Vincent Kipruto another four seconds back in third in 2:06:08.

It was the fourth triumph in five career marathons for Wanjiru and his third major triumph in a row after last August's gold medal effort in China and his London victory six months ago.

Wanjiru, 22, was one second under the old Chicago Marathon mark set in 1999 by Morocco's Khalid Khannouchi.