Sri Lanka's campaign in the Twenty20 World Cup suffered a blow today with their off-spinner Muttiah Muralitharan being ruled out of the entire tournament due to a groin strain. Muralitharan sustained the injury during his side's two-wicket defeat against New Zealand in the tournament opener on April 30.Sri Lanka meet Zimbabwe in Guyana today ( 7 P.M.) in a must-win encounter to have any chance of advancing to the Super Eight stage.In another fixture tonight (11 P.M.), England face the West Indies.