Richard Levi was left to rue Northants’ ‘capitulation’ with the bat as Warwickshire started to take control at the County Ground.
Northants were bowled out for just 147 after winning the toss and electing to bat.
Ryan Sidebottom claimed six wickets for Warwickshire, who finished the first day of the County Championship Division Two encounter on 113 for three.
Northants had taken early wickets, with Richard Gleeson (2-33) and Ben Sanderson (1-7) doing the damage.
But Warwickshire rebuilt thanks to an unbeaten 51 from Sam Hain and 39 not out from opener Will Rhodes.
“At one stage we were 100 for three and to capitulate to 147 isn’t really good enough,” said South African batsman Levi, who top scored for Northants with 41 from 76 balls.
“They did bowl well, dried it up when they needed to and it is a pitch where wickets fall in clumps.
“It’s not the easiest wicket to score on, the outfield is slow but you can score runs if you’re willing to grind it out a bit.
“We bowled well and the door was ajar but we just didn’t kick it open.
“We had quite a simple plan on that wicket and they didn’t go anywhere but we went away from that as the evening went on.”