Sri Lanka is through to the Twenty20 World Cup final after a sensational opening over by Angelo Mathews helped it to a 57-run drubbing of West Indies in the semifinals on Friday. Sri Lanka will play Pakistan in Sunday's final at Lord's. Mathews astonishingly took three wickets for a single run in West Indies' first over, as it chased Sri Lanka's total of 158-5. Mathews, who made his Twenty20 international debut at this event, finished with 3-16, Muttiah Muralitharan took 3-29 and Ajantha Mendis 2-9 off four overs as West Indies was all out in less than 18 overs for 101, despite an unbeaten 63 from captain Chris Gayle at The Oval. Earlier, Tillakaratne Dilshan smashed 96 not out in 57 balls, including 12 fours and two sixes in equaling the third highest score in international Twenty20 history. Sri Lanka captain Kumar Sangakkara said Dilshan's fireworks and Mendis' bowling were crucial. “I think the total we got was quite a big one, but we owe everything to Dilshan,” he said. “I think he (Mendis) has already won enough games for us to be a great spinner, in Twenty20 cricket and in all forms of cricket. He has been an absolute charm for us.” Gayle said Dilshan was “unstoppable” and admitted his side was blown away by Mathews. “I expected him to open the bowling because he's been doing it in the last couple of matches,” Gayle said. “But we kept losing wickets and it was downhill from there.” West Indies won the toss and opted to field. After a sedate start, the innings came to life in the fourth over when Dilshan ducked under a slow bouncer from Jerome Taylor and improvised a pull for four. He produced his trademark scoop to hit a six from the next delivery. In the next over, Sri Lanka took 13 off Dwayne Bravo. The breakthrough came in the 11th over. Jayasuriya had struggled and changed his bat three times before he was caught by Taylor at short fine leg off Bravo for 24 in an over that conceded only a single. Two balls later, Sangakkara was caught for 0 by Kieron Pollard. In the 12th, Taylor removed Mahela Jayawardene for 2, caught by Shivnarine Chanderpaul. Bravo finished with 2-32. Dilshan reached his 50 from 30 balls in the 13th but, with none of his partners able to score freely, he decided to take on the bowlers virtually singlehanded. He hit three fours off Bravo in the 17th over to complete a 50-run partnership with Chamara Silva. Just as Silva seemed set, he tried to reverse sweep and was caught by Denesh Ramdin off Sulieman Benn for 11 in the 18th. In the penultimate over, Darren Sammy produced an excellent diving catch to dismiss Jehan Mubarak for 7 off Taylor. Dilshan went into the final over on 91 and added three from the first two legitimate deliveries. Matthews hit a six, then a four, leaving Dilshan needing a six from the last delivery to score a century. He hit Gayle to long off but could scramble only two. On any other day Dilshan would have been the Man of the Mmatch, but within six balls Mathews stole the attention. Xavier Marshall, Lendl Simmons and Bravo were all bowled, from the second, fourth and sixth balls of the opening over respectively, as West Indies lurched to 1-3. Gayle and Chanderpaul made a partial recovery but the run rate was already nearly 10 when Mendis trapped the latter lbw on 7 in the ninth over. In the 11th, Mendis dropped Ramnaresh Sarwan off Lasith Malinga at long on, but he was out next over to Muralitharan, caught by Matthews attempting a nearly identical shot on 5. Pollard was stumped off a wide delivery from Muralitharan in the 14th over for 3, by which point West Indies needed more than two runs per ball. Next over Ramdin was caught by Jayawardene off Isuru Udana for 9. Gayle at least went down fighting, pulling Muralitharan for six with the first ball in the 16th, but two balls later it was 95-8 as the same bowler had Taylor caught by the sub, Nuwan Kulasekera. Sammy was caught by Mubarak off Mendis next over on 1, and the rout was completed when Malinga bowled Sulieman Benn for the fourth duck of the innings with 14 balls to spare. Brief scores: Sri Lanka 158-5 (T. Dilshan 96 n.o., S. Jayasuriya 24, A. Mathews 12 n.o, Taylor 1-31, Bravo 2-32, Benn 1-24, Pollard 1-14). West Indies 101 in 17.4 overs (C. Gayle 63 n.o., Mathews 3-16, Udana 1-20, Malinga 1-24, Mendis 2-9, Muralitharan 3