Derbyshire 252 (Godleman 53, Smith 3-23) and 37 for 0 trail Glamorgan 410 for 9 dec (Ingram 89, Meschede 70, Footitt 4-89) by 288 runs
Glamorgan's push for what would be a record-breaking victory was held up by a combination of determined batting and rain on the third day of the Division Two match against Derbyshire at Chesterfield.
When the weather closed in with 23 overs still to bowl, Derbyshire were 37 without loss following-on, still 121 runs away from avoiding an innings defeat and with a lot of batting ahead of them to deny Glamorgan five consecutive championship victories for the first time in their history.
The home side fell nine short of the follow-on target when they were bowled out for 252 with opener Billy Godleman the only batsmen to pass 50 while seamer Ruaidhri Smith returned career-best figures of three for 23 in 11 overs.
The leaden skies at the start of play made conditions good for bowling and Derbyshire were soon in trouble as the ball swung for Graham Wagg and Michael Hogan.
Derbyshire needed a substantial stand between Godleman and skipper Wayne Madsen but that was ended in the fourth over of the morning when Hogan found some late movement to have Madsen caught at third slip for 24.
Godleman's resistance ended when Wagg swung one back in and when Wes Durston was squared up in the former Derbyshire all-rounder's next over, the home side had lost three wickets for seven runs in 17 balls.
Shiv Thakor and Alex Hughes added 44 in 17 overs but David Lloyd had Hughes taken at second slip and Thakor should have gone on 17 in the next over from Craig Meschede but Hogan spilled a low chance at third slip.
Smith accounted for Harvey Hosein and Tony Palladino and when Thakor skied a sweep at Andrew Salter, Tom Taylor tore into Hogan, pulling and driving him for three sixes before the Australian bowled him on the stroke of tea.
With conditions unsettled and still favourable for bowling, Glamorgan immediately enforced the follow on but Godleman and Hamish Rutherford were largely untroubled in the 18 overs before bad light resulted in the sixth and final stoppage of the day.
It was a frustrating end for Glamorgan, but skipper Jacques Rudolph said: ``I thought the way we bowled in those last 17 overs we deserved one or two wickets. They played really well but I still think the game is wide open and if we start well in the morning we can put them under some real pressure.''
Madsen said: ``I think with the forecast being fair tomorrow we are going to have to bat most of the day which is possible. We batted for 80 odd overs in the first innings and we will probably have to bat for over 110 and get ahead so the realistic objective for us is to try and bat through the day.''