Defending champions West Indies defeated Pakistan by 84 runs to enter the semi-finals of the ICC World Twenty 20 tournament at Mirpur yesterday.In the first semi-final tomorrow, West Indies will clash with Sri Lanka , while India will take on South Africa in the second semi-final on Friday. The title clash of the competition is slated for Sunday.In the day's other Group-II match, which was a dead rubber, Australia defeated the hosts by 7 wickets in their final pool match at Dhaka yesterday.