Ninth-ranked Pakistan need to win the five-match series to stay in contention for a place in the eight-nation Champions Trophy in England in 2017.
Sri Lanka, currently ranked fifth, are assured of taking part in the tournament.
Pakistan won the preceding Test series 2-1.
Sri Lanka: Angelo Mathews (capt), Kusal Perera, Tillakaratne Dilshan, Lahiru Thirimanne, Upul Tharanga, Dinesh Chandimal, Milinda Siriwardene, Thisara Perera, Seekuge Prasanna, Suranga Lakmal, Lasith Malinga.
Pakistan: Azhar Ali (capt), Ahmed Shehzad, Mohammad Hafeez, Babar Azam, Shoaib Malik, Mohammad Rizwan, Sarfraz Ahmed, Anwar Ali, Yasir Shah, Rahat Ali, Mohammad Irfan.
Umpires: Ian Gould (ENG) and Ranmore Martinesz (SRI)
TV umpire: Rod Tucker (AUS)
Match referee: Javagal Srinath (IND)