Debutant Laurie Evans hit his second half-century in as many innings as Northants built a commanding lead at Glamorgan on day three of their County Championship Division Two clash.
After the hosts were eventually bowled out for 236, with Neck Selman making an impressive unbeaten 122, Northants overcame a sticky start to finish on 230 for seven.
That means David Ripley’s men will go into the final day 315 runs ahead, with Sean Terry (18no) and Graeme White (21no) the men in the middle.
Glamorgan had started day three on 139 for five and they made another 23 runs before losing their next wicket, with Rory Kleinveldt trapping Andrew Salter LBW for 24.
Ben Sanderson struck next, removing Rhodri Smith, before one wicket for Rob Keogh and two for White finished off the innings.
Northants lost Ben Duckett and Rob Newton cheaply in their second innings, but Evans, signed on loan from Warwickshire earlier in the week, racked up a fine 73 to go with his 74 in the first innings.
Keogh made 36 and Kleinveldt, who had blasted 91 from 88 balls in the first innings, smashed 32 from just 17 balls as Northants piled on the runs.
And Glamorgan are now faced with a big task to save the game on the final day as bottom side Northants seek their first Championship win of the season.