Sri Lanka have reached the final of cricket's Asia Cup thanks to a 129-run victory over Afghanistan in Dhaka.

Following a top score of 76 from Kumar Sangakkara and quickfire 45 from Angelo Mathews, underdogs Afghanistan had a total of 254 to chase down.

Afghanistan's star batsman Mohammad Shahzad hit a six in the second over but was out two balls later when Suranga Lakmal's delivery took out his off-stump.

Noor Ali Zadran (21) and Asghar Stanikzai (27) built a decent partnership but Afghanistan never looked likely of causing an upset on a slow pitch.

Mohammad Nabi hit Afghanistan's other six on his way to a top score of 37, but below him there was little batting as the tail fell quickly from 121-6 to 124 all out.

Sri Lanka, whose bowling was led by Ajantha Mendis, are now guaranteed a place in the final as they are the only one of the five nations taking part to win all three of their matches.

Their final group game is against Bangladesh on Thursday, while Afghanistan take on India Wednesday.