Gloucestershire 380 and 217 for 6 (Dent 81*, Cockbain 67) lead Worcestershire 411 (Clarke 135) by 186 runs
Chris Dent maintained his impressive early season form as Gloucestershire put promotion-fancied Worcestershire under pressure on the third day of the Division Two match in Bristol.
The 25-year-old left-hander followed up a big hundred against Derbyshire and 59 in the first innings of this game with a rock solid 81 not out off 175 balls to help the hosts to 217 for 6 in their second innings at the close, a lead of 186. Matt Henry claimed 3 for 60.
Ian Cockbain (67) gave good support in a second-wicket stand of 108 after Worcestershire had been bowled out for 411, Joe Clarke top-scoring with 135, backed up by Ben Cox (69) and Henry (42 not out).
The morning session saw Clarke add 32 to his overnight score after Worcestershire resumed their first innings on 297 for 5. The 19-year-old was dropped on 106 by Cockbain at point off Kieran Noema-Barnett, but otherwise built soundly on his second day hundred.
Clarke had hit 17 fours when ninth man out, bowled by Liam Norwell with a good delivery that surprised him by nipping back off the seam.
His overnight partner Cox had been equally surprised by the first ball of the day from Noema-Barnett, which somehow split his bat in two as he played defensively.
After summoning a replacement Willow, Cox added ten to the 59 he scored on day two before being caught behind by the diving Gareth Roderick off Norwell.
Joe Leach was bowled shouldering arms to a David Payne inswinger and when Ed Barnard was well held by Dent at second slip, driving at Norwell, Gloucestershire looked favourites for a first-innings lead.
But Henry then contributed to stands of 39 with Clarke and 41 with last man Jack Shantry to ensure his side of maximum batting points and a lead of 31.
Gloucestershire overtook the deficit without losing a wicket as Dent and Cameron Bancroft put together and opening stand of 49 before the latter was caught behind off Barnard for 29.
Dent was unbeaten on 46 at tea, having added 80 with a confident looking Cockbain, who reached his half-century two balls after the interval by pulling Leach for his tenth boundary.
Cockbain was particularly impressive when driving and didn't play like a batsman who managed only 139 Championship runs last season at an average of 13.9.
Dent soon followed him to a more sedate fifty off 102 balls with 8 fours. But, with Gloucestershire getting on top, Leach struck twice in the same over, taking a return catch off a leading edge to dismiss Cockbain and then pinning Gareth Roderick lbw with a full delivery for a third ball duck. First-innings centurion Hamish Marshall had made 17 when bowled by Henry with the lead 159 and the Kiwi paceman followed up by dismissing George Hankins and Noema-Barnett with successive balls in an impressive late burst from the Ashley Down Road End. But Dent stood firm to keep Gloucestershire hopes alive.
Worcestershire captain Daryl Mitchell said: "Matt Henry's spell at the end of the day has put us in with a great chance. I would be happy to chase any reasonable figure tomorrow because the pitch remains a very good one. "We have a new ball due before too long and it has nipped around more in the morning sessions, so hopefully we can take the last four wickets pretty quickly.
"What a prospect Joe Clarke is. He played exceptionally well for his 135 and is a big presence in our changing room for a 19-year-old lad. He has a fantastic future and it was a terrific knock in a difficult situation."