Abu Dhabi: Sri Lanka were fighting to save the first Test under a heavy 300-plus deficit after Pakistani opener Taufiq Umar hit his maiden double hundred on the third day on Thursday.
Shot out for a low score of 197, Sri Lanka closed on 47-1 after Umar hit a sedate 236 to lift Pakistan to 511-6 declared in their first innings at Abu Dhabi stadium.
Sri Lanka, who conceded a 314-run lead, still need another 267 runs to avoid an innings defeat with the pitch showing sings of turn which Pakistan's off-spinners Saeed Ajmal and Mohammad Hafeez will likely to exploit.
Paceman Umar Gul struck with the first ball of the second innings, trapping Tharanga Paranavitana before Lahiru Thirimanne (20) and Kumar Sangakkara (27) survived some anxious moments to see off the day.
It was Umar's typical Test match knock which held the Pakistani innings together, adding invaluable runs with Azhar Ali (70), Younis Khan (33), Misbah-ul Haq (46) and Asad Shafiq (26 not out).
Umar's is the first double hundred by a Pakistani opener since Aamir Sohail's 205 against England at Old Trafford in 1992, highlighting the lack of quality openers and their regular chopping in the country's team.
The 31-year-old left-hander hit 17 boundaries and a six during his marathon 700-minute stay at the crease, showing immense concentration and application, before he ran out of stamina and was run out.
He batted solidly, consumed 496 deliveries to notch the second highest Test score by a Pakistani opener behind Hanif Mohammad's 337, made against the West Indies at Bridgetown in 1958.
Umar added 160 for the second wicket with Ali, 82 with Younis for third, 76 with Misbah for the fourth and 75 with Shafiq for the fifth.
Pakistan resumed at 259-1 with overnight pair of Umar and Ali extending their second wicket stand as they again remained unflappable on a pitch that gave little response to pace and spin.
Ali, who has 10 half centuries in 14 Tests now, yet again failed to register his maiden hundred as he came late on a swinging delivery which uprooted his off-stump. Ali struck six boundaries.
Younis had a shaky start as he was beaten by Welegedara first ball and was then dropped by Prasanna Jayawardene off skipper Tillakaratna Dilshan when a leg-side edge was dropped by the wicket-keeper despite getting two attempts.
Umar, 31, remained steady as he hit a glorious boundary off Suranga Lakmal and then took a single off Herath to go past his previous best score of 135, made on two occasions.
He hit 135 against South Africa at Cape Town in 2003 and repeated that score against the West Indies at St. Kitts earlier this year.
Younis was trapped leg-before by paceman Chanaka Welegedara.
Misbah added a quickfire 76 with Umar for the fourth wicket before he was caught behind off left-arm spinner Rangana Herath who finished with 3-126.
The three-Test series is played at the neutral venues of United Arab Emirates after Sri Lanka turned down an invitation to tour Pakistan over security fears.