Glamorgan 433 and 88 for 0 (Rudolph 56*) trail Gloucestershire 558 (Dent 268, Fuller 73) by 37 runs
Chris Dent's superb career-best 268 put Gloucestershire in the ascendancy against old foes Glamorgan on the third day of their Championship match at Bristol.
Gloucestershire's formidable total of 558, founded upon a record-breaking stand of 166 between Dent and James Fuller, helped the home side establish a meaningful first-innings lead of 125. But a draw appears the most likely outcome after Glamorgan openers Jacques Rudolph and James Kettleborough overcame fatigue to negotiate 27 overs and reach the close on 88 without loss.
Rudolph's chanceless innings of 56 not out has occupied 87 balls and the captain will seek to steer his side, who trail by 37, to safety on the final day.
On a day when the records tumbled, Dent posted the highest individual score by any Gloucestershire batsman in matches against Glamorgan since World War II, eclipsing the 254 made by Andrew Symonds at Abergavenny in 1995.
His run-laden alliance with Fuller, who registered a career-best 73 from 99 balls, represented a club record stand for the eighth wicket in matches against Glamorgan, surpassing the 128 mustered by Mark Hardinges and Ashley Noffke at Bristol in 2007.
And Dent comfortably bettered his previous highest first-class score of 203 not out, made against Cardiff MCCU in 2014, in the process becoming the only Gloucestershire player to pass 1000 first-class runs this season.
Dropped by Colin Ingram in the slips before he had scored, Fuller made good his escape to eclipse his previous highest score of 57, made against Leicestershire at Cheltenham in 2012.
With the exception of a couple of early setbacks, Benny Howell shouldering arms and losing his off stump to Michael Hogan without adding to his overnight score of 40 and Kieran Noema-Barnett chipping Craig Meschede straight to point for 5, it was pretty much plain sailing for the home side.
Dent and Jack Taylor, who raised 35 from 33 balls and struck seven fours before top-edging a catch behind off Dewi Penrhyn-Jones, redressed the balance in an entertaining stand of 53 for the sixth wicket.
With Gloucestershire opting to apply scoreboard pressure rather than pursue a contrived finish, Dent was presented with a chance to post a maiden Championship double hundred. In no mood to pass up such an opportunity, the Bristolian clipped Penrhyn-Jones to backward point and scampered a quick single to reach the mark in the 98th over. When he guided Graham Wagg to the fine leg boundary in the next over, the left-hander entered hitherto uncharted territory and County Ground regulars rose to acknowledge his achievement.
Fuller must have had one eye on a maiden hundred when he advanced down the track to Andrew Salter and attempted to clear the long-on boundary, only to find Penrhyn-Jones, who took a fine catch just inside the rope.
David Payne was bowled by Salter shortly after tea and Dent, having batted for eight hours, faced 347 balls and accrued 34 fours and 2 sixes, was last man out, superbly held by Wagg on the deep midwicket boundary off the bowling of Meschede. It proved tough going for Glamorgan's seamers and Australian Hogan was the only bowler to emerge with credit, returning figures of 3-83.