Glamorgan 168 (van der Gugten 46*, Chappell 6-47) and 236 for 7 (Carlson 56, Ingram 53, Morley 3-35) trail Derbyshire 429 (Dal 94, Came 84, Madsen 70, Crane 3-43, Kellaway 3-59) by 25 runs

After rain washed out the morning session, Brown and Zak Chappell started Glamorgan's decline with three wickets in six overs. Billy Root did not profit from his escape the previous evening, scoring only 13 before he pushed at a ball from Brown he could have left and was caught behind.

Brown tempted Ben Kellaway into a loose waft that gave Brooke Guest another victim before Chappell bagged the big wicket of Sam Northeast. The Glamorgan skipper had started purposefully but there was little he could do with a ball that was angled in and straightened enough to get through his defence and pluck out middle stump.

A shower held up play for 20 minutes which would have helped keep the bowlers fresh and disrupt the batters concentration but both Carlson and Ingram settled in well after the restart. Carlson was more circumspect after he got away with a big drive early in his innings and Ingram, who scored a century on this ground last season, was quick to pounce on anything short or overpitched.

With Anuj Dal off the field, Derbyshire were a bowler down and there was frustration for Brown when Carlson saw an edge loop just over third slip before Ingram was given a life on 25. Brown tempted him into a drive and the edge went low to Guest who could not hang on diving to his left.

Ingram reached his 50 off 93 balls the over before tea which arrived with Glamorgan recovering well to get the deficit below three figures. But all the hard work was undone three overs into the final session when Ingram attempted a big slog-sweep at Morley and was bowled to end a stand of 110 from 179 balls.

Derbyshire thought they had Carlson in the next over, caught behind off David Lloyd, but the umpires ruled correctly that the ball had been played into the ground.

Carlson completed his 50 off 125 balls before Derbyshire lost Brown who limped off with what appeared to be an ankle injury four overs into his second spell.

Lloyd took over and struck when Chris Cooke tried to drive and was bowled, breaking a stand of 50 from 122 balls. Derbyshire moved a step closer to victory in the next over when Carlson inexplicably gave Morley the charge and was stumped.

Timm van der Gugten was lbw first ball and although Mason Crane averted the hat-trick, Glamorgan will need something remarkable on the last day to deny Derbyshire that long-awaited home win.