Afghanistan continued their rise in international cricket with an upset 91-run win over Sri Lanka in Abu Dhabi on Monday, knocking the former champions out of the Asia Cup.

Sri Lanka needed to win the Group B match to stay in the tournament but were outwitted by smart batting from Afghanistan who put up a fighting total of 249 all out at Sheikh Zayed Stadium.

The fighters then laid into Sri Lankan batting with spinner Rashid Khan (2-26), Mohammad Nabi (2-30) and Mujeeb Ur Rahman (2-32) sharing wickets as the five-time former winners were bowled out for 158 in 41.2 overs.

Sri Lanka did not help their cause with two run outs while skipper Angelo Mathews played a reckless shot off Nabi and was caught near the boundary for 22.

This becomes Afghanistan's first-ever victory against Sri Lanka in three one-day internationals after losing in the Asia Cup 2014 and World Cup a year later.

Sri Lanka, who now have lost 30 of their 40 matches since January 2017, had lost to Bangladesh by 137 runs in Dubai on Saturday.

Bowled out for a paltry 124 against Bangladesh, Sri Lankan batting again failed miserably with only Upul Tharanga (36) and Thisara Perera (28) offering some fight.

Afghanistan were helped to 249 all out in their 50 overs with Rahmat Shah scoring 72 and Ihsanullah Janat shipping in with 45.

Shah struck five boundaries during his 90-ball knock and added 50 for the second wicket with Janat (45) after Afghanistan won the toss and opted to bat on a flat pitch.

Janat hit six boundaries in his 65-ball innings while his opening partner Mohammad Shahzad batted in his aggressive style, hitting a six and four boundaries in his 47-ball 34.

Rahmat then added another 80 runs for the fourth wicket with Hashmatullah Shahidi who made a sedate 52-ball 37.

For Sri Lanka seamer Thisara Perera took five for 55 and spinner Akila Dananjaya finished with two for 39. Defending champions India, Pakistan and qualifier Hong Kong are placed in Group A.

Pakistan beat Hong Kong by eight wickets in Dubai on Sunday.

Top two teams from each group will qualify for the Super Four stages from where top two teams will play the final in Dubai on September 28.

India face Hong Kong in Dubai on Tuesday before their high profile match against Pakistan a day later at the same venue.