Geoffrey Kirui of Kenya crosses the finish line to win the men's division of the 121st Boston Marathon in Boston, Massachusetts, US, April 17, 2017. [Photo/Agencies]

Kirui finished in two hours nine minutes and 37 seconds after holding off a challenge by American Galen Rupp in the race's final stretch down Boylston Street, the site of the deadly 2013 bombing attack.

Kirui repeatedly tested Rupp in the closing miles, with the American Olympic bronze medalist eventually unable to match the Kenyan's pace.

"He put in several surges and I was able to cover a few of them," Rupp told reporters after the race.