Pakistan needed 178 runs to win the second test and sweep the series, while West Indies were six wickets short of levelling the two-match series after the second day at Multan on Sunday.
West Indies ended their second innings on 244 as spinners Noman Ali and Sajid Khan took four wickets each. The visitors set a target of 254 for Pakistan, who trailed by nine runs after the first innings.
West Indies captain Kraigg Brathwaite (52) gave the visitors a strong start in the second innings with a 50-run opening partnership before Mikyle Louis (7) fell to Noman.
West Indies was struggling at 145-6 as Noman surrounded the newly-arrived Sinclair with two short slips and a silly point, hunting for an edge as the ball turned heavily and kept low.
Sinclair, however, scored 28 in a 51-run partnership for the seventh wicket with Tevin Imlach (35) before being bowled out by Khan.
Kemar Roach, who suffered a groin injury during a spectacular diving catch on Saturday, was the last to bat, limping and running gingerly.
But the 36-year-old did not give up his wicket, scoring four runs in a valuable 11-run partnership with Jomel Warrican (18).
Pakistan got off on the wrong foot with openers Masood (2) and Muhammad Hurraira (2) trapped leg before wicket, fooled by deliveries that kept straight instead of turning.
Kamran Ghulam (19) started well but mistimed an attempt to hit Warrican for six, finding Jangoo at backward point, leaving Pakistan struggling at 48-3.
The situation soon worsened for the hosts as Azam (31) was bamboozled by Sinclair’s sharp bounce and edged it to Alick Athanaze.
Saud Shakeel (13) and Kashif Ali (1) remained at the crease at stumps, with the fate of the match and the series hanging in the balance going into day three.
