Pakistan were bowled out for 383 in their first innings on the stroke of lunch on the third day of the first Test in Abu Dhabi Thursday.
Resuming at 327-4, Pakistan added another 56 runs before losing their last six wickets to take their lead to 179 on Sri Lanka's first innings score of 204.
Younis Khan got 136 while skipper Misbah-ul Haq scored 135.
Left-arm spinner Rangana Herath took 3-93 while paceman Shaminda Eranga finished with 3-80.