Experts divided over chances of sub-two hour marathon

Assuming conditions are conducive to fast running - cool and not too windy - all three predict a time inside Dennis Kimetto's 2014 world record of two hours, two minutes, 57 seconds when Kenyan Olympic champion Eliud Kipchoge, Ethiopia's Lelisa Desisa and Eritrea's Zersenay Tadese take to the Monza motor racing track, aided by a group of "in and out" pacemakers.