Hambantota - Five South African players have fallen ill but are expected to be fit for the team's first World Twenty20 match against Zimbabwe on Thursday."We have a few guys who have gone down with viral infection, vomiting and diarrhoea but I am happy to say that they are on the mend," team manager Mohammed Moosajee said on Wednesday."I am hopeful come tomorrow, all 15 will be fit to take the field," he said while declining to identify the players struck by illness.On Monday, three members of New Zealand's World Twenty20 team - Tim Southee, Rob Nicol and Daniel Vettori - suffered stomach trouble.For South Africa, all-rounder Albie Morkel is also doubtful for Thursday's match because of a back problem."Albie will be having a fitness test tomorrow morning," said Moosajee."The results of the MRI scan we took yesterday were inconclusive."There is a chance that he might play, but we don't want to take any chances," he said.Morkel bowled nine balls in South Africa's warm-up match against New Zealand on Monday before leaving the field due to lower back spasms.