Kusal Perera posted a knock of 84 to help Sri Lanka set Pakistan a total of 212 to win the second Twenty20 international in Dubai.
Pakistan won the toss and decided to bowl, but they had their work cut out as Sri Lanka took the game to their opponents.
Perera and Tillakaratne Dilshan (48) put on an opening partnership of 100 before the latter was caught by Umar Amin off the bowling of Saeed Ajmal.
Seekkuge Prasanna hit 21 off eight balls, but he became Ajmal's second victim of the innings when he lofted a simple catch to Usman Khan.
Kumar Sangakkara supported Perera with a quickfire 44, until Perera was run out by Ajmal on the final delivery as Sri Lanka ended their innings on 211-3.