Denly survived an early dropped catch to be unbeaten on 45 at the break after West Indies had started brightly.
Keemo Paul had Rory Burns (10) out to a regulation catch at square leg by Alzarri Joseph on the first ball of the day to put England at 19 for 1. But then it all began falling apart for the home sides pace attack, and none more so than Paul.
With menacing quick Shannon Gabriel apparently carrying a hamstring injury, he then suffered the insult of a dropped catch by Shimron Hetmyer at third slip off Denly when the batsman was not out 12. Suggestions the delivery may have been a no ball would have been little comfort to the snarling Gabriel.
In the meantime, Paul was prostrate on the grass just outside the boundary rope, having pulled up in agony as he chased down a Denly cover drive two balls earlier. Paul - who had come into the side to replace suspended captain Jason Holder and claimed two wickets in Englands first innings, including that of Keaton Jennings with his first ball of the match - ended up having to be stretchered away with a right quadriceps strain.
Initial reports from the West Indies camp suggested Paul would not return to the field before tea, although the manner in which he went to ground and the fact he had to be wheeled away gave cause for serious concern. His injury meant the home side had to call upon a second substitute fielder, Jomel Warrican, with Darren Bravo already off receiving treatment for a finger injury picked up earlier in the match.
A bowling change delivered some much-needed reward for West Indies when Joseph snared the wicket of under-pressure Jennings with a ball that was missing everything before it jagged the thigh pad and curled behind the batsman onto leg stump. Jennings grinned ruefully after the freak end to his innings. With scores of 17, 14, 8 and 23 in this series, having been dropped in favour of Denly for the second Test in Antigua, he perhaps realised that his time as an England Test batsman could be over.
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