The International Cricket Council had confirmed on Saturday that the event's technical committee has approved Thushara as replacement for Murali, who has been struggling with a groin injury.As per the tournament rules once replaced, a player cannot return, which means Twenty World Cup is over for Murali.
The star off-spinner suffered the injury during Sri Lanka's tournament-opening loss to New Zealand in Guyana and missed his side's subsequent victory over Zimbabwe.
Murali, however, turned out in Sri Lanka's 57-run win over the West Indies in the Super Eight stage match here last Saturday.
Left-arm pacer Thushara has represented Sri Lanka in nine Tests, 36 One-Day Internationals and five Twenty20 Internationals, the last of which was against Pakistan in August, 2009.