Bhanuka Rajapaksa smashed an unbeaten 71 to guide Sri Lanka to 170-6 after Pakistan's Haris Rauf rattled the opposition with early wickets in the Asia Cup final on Sunday.

The left-handed Rajapaksa put on a key 58-run stand for the sixth wicket with Wanindu Hasaranga, who hit 36, to help Sri Lanka to a competitive total after they were in trouble at 58-5 in Dubai.

Rauf stood out with figures of 3-29 off his four overs of pace.

Pakistan won the toss and skipper Babar Azam had no hesitations in fielding first in Dubai with nine of the 12 matches won by the team chasing in the tournament, a curtain-raiser for next month's T20 World Cup in Australia.

Pace bowler Naseem Shah struck in the opening over as he bowled Kusal Mendis for a first-ball duck with a searing inswinger.

Dhananjaya de Silva hit back with two flowing off drives for boundaries off Mohammad Hasnain to get the innings rolling.

Pathum Nissanka attempted to play his shots in the first six overs of powerplay but miscued Rauf and was caught at mid-off.

Rauf sent the off stump cartwheeling in his second over to send Danushka Gunathilaka trudging back to the pavilion as Sri Lanka slipped to 36-3.

Wickets kept tumbling with De Dilva's innings cut short by Iftikhar Ahmed on 28 and skipper Dasun Shanaka bowled by leg-spinner Shadab Khan on two as a packed crowd, dominated by Pakistan fans, erupted.

Rajapaksa and Hasaranga got together to rebuild the innings as the two hit regular boundaries to up the scoring rate.

Rauf dismissed Hasaranga, who hit five fours and one six in his 21-ball knock, caught behind for his 50th T20 wicket to break the dangerous stand.

Rajapaksa kept up the attack and survived a dropped catch by Shadab in the deep, soon reaching his third T20 half-century.

Rajapaksa, who finished the innings with a four and six off Naseem in his 45-ball blitz, and Chamika Karunaratne put on 54 runs to further boost the total.

Pakistan need 171 runs to lift their third Asia Cup title.