Pakistan pressed West Indies hard for a series-clinching win in the second Test after setting a daunting 456-run target on the fourth day in Abu Dhabi on Monday.
By close of play Pakistan had taken four wickets at 171 leaving the West Indies to bat out the fifth and final day on Tuesday or score a further 285 runs with six wickets intact for an unlikely win.
No team has ever chased down more than the 418-7 West Indies managed against Australia at Antigua 13 years ago and on a weary last day pitch they will need a huge effort to stop Pakistan from taking an unassailable 2-0 lead.
Pakistan won the first Test -- a day-night affair played with the pink ball -- by 56 runs in Dubai.
Pakistan had declared their second innings on 227-2 at lunch, with Asad Shafiq on 58 not out (his 16th Test half century) and Younis Khan 29 to give their bowlers enough time to force a win.
At close Jermaine Blackwood was unbeaten on 41 and with him Roston Chase 17 not out as the two foiled Pakistan's bowling during an unbroken 47-run stand for the fifth wicket.
The duo carried the fight initiated by opener Kraigg Brathwaite who scored a fighting 67 with six boundaries and a six.
Brathwaite and Marlon Samuels (23) had added 49 for the third wicket but both fell in the space of 12 runs, Samuels giving a return catch to leg-spinner Yasir Shah while Brathwaite trapped leg-before wicket by Mohammad Nawaz.
Brathwaite had completed his 11th half-century with a three run drive off paceman Sohail Khan -- his first in this series.
West Indies' task of saving the Test was made even more difficult after they lost Leon Johnson (nine) and Darren Bravo (13) with the total on 63.
Johnson tried to sweep a delivery from Shah only to drag it on to his stumps after hitting the bat and glove.
Bravo, who scored a fighting 116 in Dubai, slashed a drive off fast bowler Rahat Ali straight to point where Mohammad Nawaz held a head high catch.
SCORES IN BRIEF
PAKISTAN: First innings 452
WEST INDIES: First innings 224
PAKISTAN: Second innings 227 for 2 decl (Aslam 50, Azhar 79, Shafiq 58 not out, Younis 29 not out; Gabriel 1-36, Cummins 1-26)
WEST INDIES: Second innings 171 for 4 (Brathwaite 67, Samuels 23, Blackwood 41 not out, Chase 17 not out; Shah 2-60)