Michael Hugh Tissera (born 23 March 1939) is a former Sri Lankan cricketer who played in the 1975 Cricket World Cup. (wikipedia)
He has been playing club cricket at home and he has been batting and bowling, so he is fine.
He is as good a chance as anyone else to play.
All three players have been ruled out of the entire one-day series.
It's a back spasm but nothing serious, we're expecting him to be fit.
He should be ok. He just had a little bit of a thigh strain but it's fine.