ANY result remained possible until Chris Rushworth struck with the last ball before tea to tip the balance in Durham’s favour.
Northants will go into the final session on 125 for five, still needing 194 from 32 overs.
He and James Middlebrook put on 37 in 14 overs before the latter drove at Usman Arshad and sliced to backward point, where Gareth Breese held a tumbling catch.
The Andrew Hall quickly showed that Northants were still prepared to go for it as he opened up with two fours off Arshad.
Chris Rushworth made the breakthrough two overs after lunch when he had Stephen Peters caught behind by Phil Mustard.
But Durham weren’t helped when the wicketkeeper spilled a regulation chance off Onions with Middlebrook on 15 as the Yorkshireman completed his impressive all-round display by making 47.
Onions bowled Kyle Coetzer with a shooter, but there were few other signs of the pitch starting to misbehave.
Two overs later he knocked out Matthew Spriegel’s off stump as the left-hander followed his first innings 97 with a duck.
Rushworth came back for a second spell in place of Arshad and had Hall lbw for 13.