Seven, Andy and Bes,
Do you think a football match needs more efforts than a battle??
Do you know that most of the important battles in the Islamic history were during Ramadan month where all Muslims were fasting??, For example, Badr Battle, Fateh Mecca and even during 1973 war between Arabs and Israel. The history just witnessed how the fasting people in these battles did against their opponents although their number was much less.
Fasting was never an execuse for being lazy except when the faster is not totally convinced with the reason of his fasting, and that is not the case, I guess for a player like Sissoko, who has the option as you all know to fast or not during the matches days as Turk said ealier because travelling just gives you the permission not to fast in that exact day.