West Indies held a 155-run lead over Pakistan with three wickets remaining in their second innings at the end of the third day of the first Test on Monday, after a day dominated by the bowlers.
Justin Greaves claimed his first five-wicket haul in Test cricket, taking 5-27, as Pakistan lost six wickets for just 38 runs after Shan Masood completed his seventh Test century.
Pakistan, who resumed the day at 199-3, were 244-4 when Masood reached 109, but collapsed to 282 all out, giving West Indies a 29-run first-innings lead after the hosts had made 311.
Mohammad Abbas then produced another impressive spell with the new ball, taking 3-14 in 13 overs as West Indies slipped to 126-7 at stumps.
Kemar Roach was unbeaten on five, while Shamar Joseph struck a quick 22 off 13 balls as the hosts sought to build their lead toward 200, which would present Pakistan with a challenging fourth-innings chase.
Masood reached his century from 163 balls after resuming on 88. He and Salman Agha initially made steady progress as Pakistan looked well placed to match or surpass West Indies' first-innings total.
But Shamar Joseph changed the momentum when he bowled Agha for 20 with a delivery that seamed past the outside edge, leaving Pakistan at 244-4.
Greaves then removed Masood, who was bowled after an inside edge sent the ball onto the stumps.
Aamir Jamal was dismissed for three after missing a straight delivery from Greaves. Ali Usman was then trapped lbw for a duck, while Mohammad Rizwan was caught behind for 12, leaving Pakistan at 259-8 before lunch.
Greaves completed his five-wicket haul when Abbas was caught behind, and Pakistan were soon bowled out when Roach dismissed Khurram Shahzad for 19.
Abbas continued his impressive form in West Indies' second innings, dismissing Brandon King for five and Kavem Hodge for a duck to reduce the hosts to 7-2 in the fifth over.
Mohammad Ali then caught Amir Jangoo for four off his own bowling before Khurram Shahzad bowled Shai Hope for 10, leaving West Indies at 43-4.
Tagenarine Chanderpaul offered some resistance with 35 before Aamir Jamal dismissed him.
Abbas returned to remove Greaves for 20, while Shahzad claimed the wicket of West Indies captain Roston Chase for eight.
Roach and Joseph then steadied the innings, with Joseph attacking Pakistan's bowlers in an effort to extend the lead before the close.
Pakistan had entered the third day in a strong position at 199-3 after Masood's unbeaten 88 helped them recover from early setbacks.
The first Test is being played at the Brian Lara Cricket Academy in Tarouba.