Northamptonshire's sixth-wicket pair, Russell Warren and Tony Penberthy, retrieved a desperate-looking position against Glamorgan at Wantage Road before the weather intervened.
Warren (175) and Penberthy (132 not out) added 250 in 66 overs for the sixth wicket, dragging their side away from deep trouble at 127-5 on Saturday afternoon when the follow-on appeared a formality.
David Ripley's declaration on 446-7, still 102 runs behind, then kept alive hopes of an interesting finish, and the visitors closed on 66-1 - a lead of 168 with a day to go.
Resuming on 181-5, Warren and Penberthy survived the morning session with the help of some costly Glamorgan fielding errors. Warren, dropped on 25 the previous evening, was put down again on 134 by wicketkeeper Adrian Shaw off Jimmy Maher, and Penberthy should have gone with 44 to his name, only for Matthew Maynard to spill a slip chance.
Warren was eventually undone by Steve Watkin with the second new ball, having hit a six and 31 fours in his stay of five hours. His partnership with Penberthy set a new Northants sixth-wicket record against Glamorgan, eclipsing the 145 posted by Fred Bakewell and Ben Bellamy in 1934, and was only five runs short of the county's best for that wicket against any opponents at Northampton.
The Cornishman was still in possession when the declaration came, having struck 20 boundaries in an attractive 211-ball knock.
Glamorgan then lost Alun Evans, trapped leg-before padding up to Paul Taylor, but Maher and Michael Powell were going well when rain halted play for the day 20 overs early.