Gloucestershire 267 and 135 for 3 (Dent 67) trail Worcestershire 428 for 5 (D'Oliveira 91, Mitchell 80, Libby 77) by 26 runs
Worcestershire seamer Charlie Morris struck a potentially crucial blow by removing Gloucestershire captain Chris Dent shortly before the close of play on day three of the Bob Willis Trophy Central Group match at the Bristol County Ground.
Having scored 67 to add to his first innings 92, Dent was again frustrating Worcestershire's hopes of engineering a winning position in the opening game of the season. But that all changed when Morris had him caught behind in the early evening gloaming and the hosts finished the day on 135 for 3, still 26 runs behind with seven wickets in hand. Gloucestershire still have a good deal of work ahead of them if they are to save the game and the new ball, due after lunch on day four, could yet prove decisive.
Much will depend on George Hankins, who will resume on 38 not out in the morning, in partnership with nightwatchman Josh Shaw, who is yet to score.
Worcestershire had earlier added a further 205 runs to reach 428 for 5 in their 120 overs and establish a meaningful first-innings lead of 161, Brett D'Oliveira top-scoring with 91 not out, Jack Haynes registering a maiden first-class fifty and Ben Cox weighing in with a whirlwind unbeaten 48 from 32 balls.
Gloucestershire were immediately under pressure in their second innings, Miles Hammond and Graeme van Buuren departing in quick succession as the hosts slumped to 46 for 2. A cornerstone of Gloucestershire's batting, Dent refused to budge, raising his second half-century of the match from 100 balls and staging a restorative partnership of 88 in 33 overs with Hankins.
Morris made the key intervention with four overs remaining in the day and the paceman, the pick of Worcestershire's bowlers, now has six wickets to his name.
Looking to even things up when Worcestershire resumed on 223 for 2, still 44 in arrears, Gloucestershire enjoyed some early success with the new ball, removing Tom Fell, Riki Wessels and Haynes during the morning session. But their attempts to exert control were blown to the four winds after lunch.
Eager to impress in only his sixth first-class appearance and cement his place in the team, England Under-19 international Haynes shared in stands of 53 and 48 with Fell and D'Oliveira for the third and fourth wickets respectively. Initially circumspect, he faced 72 balls before hitting his first boundary, accelerating thereafter and going to a 110-ball 50 via his fourth four, punched through midwicket at the expense of David Payne.
He was out in the next over, pinned lbw by a delivery from Ryan Higgins that came back in to him. Fell had earlier perished lbw in the act of playing across the line to a straight one from Shaw, while Wessels fell into Matt Taylor's trap and was well held by van Buuren on the run at deep midwicket.
But any thoughts the home side might have entertained of restricting Worcestershire's middle order were quickly forgotten when D'Oliveira and Cox launched a fearsome assault, eight exhilarating overs after lunch spawning a remarkable 92 runs as the game dramatically switched into T20 mode.
D'Oliveira's progress was characterised by deft placement and quick running between the wickets as he registered a 79-ball half century. His next 41 runs occupied a mere 25 balls, taking advantage of some wayward bowling from Tom Price and Matt Taylor to garner 13 fours. His partner in Blitzkrieg, Cox proved equally bullish, smashing a half-a-dozen fours and lofting a length ball from Shaw straight back over the bowler's head for an imposing six as the runs flowed.