Glamorgan 187 (Donald 53, Fletcher 3-60) and 212 for 5 (Ingram 72*) trail Nottinghamshire 448 (Wessels 120, Libby 109, Hutton 61, van der Gugten 5-101) by 49 runs
With Glamorgan still trailing by 42 runs, and five wickets down in their second innings, Notts will be confident of ending their resistance sometime on the final day, so completing their fourth successive championship win of the season.
They were held up on the third day by Colin Ingram, who batted for 77.3 overs, showing the application and concentration that had been missing in Glamorgan's first innings. He was supported by the middle order, notably Aneurin Donald and David Lloyd, and during his undefeated 72, Ingram has already faced 209 balls.
After dismissing Glamorgan for 187 in 62.3 overs, Notts had no hesitation in enforcing the follow on, and Luke Fletcher responded with his first ball - the seventh of the innings- when he knocked back Nick Selman's off stump as the opener shouldered arms.
Despite a partnership of 51 for the second wicket between Jacques Rudolph and Will Bragg, both departed in successive overs as Glamorgan went to lunch 71 for 3. Bragg shuffled across his stumps and was out leg before to Harry Gurney for 30, before Rudolph, who faced 57 balls, hitting just the one four, nicked an outswinger from Brett Hutton to the stand in wicketkeeper Riki Wessels for 14.
Ingram and Aneurin Donald, who are both attacking batsmen, then got their heads down to deny Notts' bowlers any further success for the next 24.1 overs.
Donald did strike Stuart Broad for six over long leg, but then undid all his good work by getting out to a reckless shot. Two balls before his dismissal, Donald attempted to slog sweep Samit Patel as the ball narrowly missed the off stump, but two balls later he attempted the same stroke and was bowled.
The new ball became due with 16 overs remaining, but not before Ingram had reached a patient half century from 153 balls with seven fours. The South African left hander, who struck 29 sixes in the recent Royal London One Day competition, played every ball on its merit, and unlike his first innings dismissal, when he flashed at a ball outside the off stump and was caught at second slip, not once did he attempt to play at anything remotely wide of the stumps.
David Lloyd then gave Ingram solid support for the next 42.2 overs, scoring 37 from 153 balls, and was at the crease for 2 hours and 40 minutes, before getting a ball from Fletcher that lifted from a length and carried to second slip. Much now depends on Ingram if Glamorgan are to deny Notts victory on the final day.