Pakistan took an unassailable 3-1 lead in the one-day international series with Sri Lanka after an eight-wicket victory in Abu Dhabi on Christmas Day.
Chasing 226 for victory, Pakistan reached the target with 8.5 overs to spare as Mohammad Hafeez scored his third century of the series.
Sri Lanka won the toss and elected to bat first but were dismissed for 225 in 48.5 overs with Saeed Ajmal picking up 4-39.
Umar Gul picked up 3-37, removing Kusal Perera, Tillakaratne Dilshan and Dinesh Chandimal in single figures in his opening four overs.
Kumar Sangakkara and debutant Ashan Priyanjan revitalised the innings with an 87-run partnership for the fourth wicket before the former captain was run out for 51.
Priyanjan eventually departed for 74 before Ajmal ran through the lower order with only captain Angelo Mathews (38) and another debutant, Kithuruwan Vithanage (27), making contributions.
Mathews removed opener Sharjeel Khan with his first ball but Pakistan made a fast start, reaching 57-1 after 10 overs.
In-form pair Ahmed Shehzad and Hafeez put on 84 for the second wicket before the opener departed for 44, edging a length delivery from Suranga Lakmal to Sachithra Senanayake at first slip.
Hafeez, who had already scored two centuries in Sharjah, continued his rich vein of form with his third ton coming up off 98 balls.
Hafeez hit the 12th four of his innings off Dilshan to bring up his ninth ODI hundred and make history.
He finished on 113 not out with Sohaib Maqsood making an unbeaten 46 in a century partnership for the third wicket as Pakistan coasted home.