Northants head coach David Ripley believes his side are still favourites to beat Middlesex - despite a fine fightback from the away side at the County Ground.
Max Holden and James Harris have given Middlesex hope of producing a remarkable turnaround.
The pair added 121 for the seventh wicket on the third afternoon to help steer their side to 374 for nine following-on, leading by 215.
But ahead of the final day of action, Ripley said: "If you would have said on day one in the conditions that we had to come back on the final day to chase 220, we would have taken that to be honest.
“We’ve still got a good opportunity to go and win the game and we should be favourites with the wicket how it is now but we’ve still got to go and do it.
“We didn’t do a lot wrong today, we showed a lot of heart, bowlers kept coming in but two guys got stuck in and built a stand and that’s what we’ll need tomorrow.”
At 166 for six just after lunch, and a lead of just seven, Middlesex were slumping to defeat.
But Holden and Harris gathered themselves and began to work their side back into the game with careful, considered batting with the clouds parting and the zip from the surface easing.
Holden led the resistance, simply happy to occupy the crease.
He left the very ball well and nudged and flicked his way to an 83-ball 50 - his second of the summer - but it did include a sumptuous cover-drive, one of eight boundaries.
Harris was a more jittery early on and cut and missed several times and edged Brett Hutton just short of first slip. But he too was prepared to grind it out and take the innings as deep as possible.
Holden, on the ground where he spent a profitable loan spell last season, got to six runs shy of a maiden Middlesex century against the second new ball but, agonisingly, drove loosely at Hutton and edged to second slip.
He peeled himself from the field having undone all his hard work with a shot he had largely ignored for his previous 163 balls.
After Holden fell, the lead was only 128 and Northants had ambitions to run through the lower order.
But Harris wasn’t finished and went past his own half-century - a third in this year’s Championship - in 138 balls with seven fours.
Harris managed to take Middlesex to the close, 79 not out, sharing a stand of 54 with 19-year-old Ethan Bamber, on debut, and No. 11 Tim Murtagh then holding out to stumps.
“We were obviously in a tricky position and I’m really pleased I was able to contribute and help get us back into a good position," said Middlesex batsman Holden.
“We’ve made a habit of not starting games as well as we would have liked but the character the guys have showed is testament to the team’s attitude.
“We’re in a good position to win now because I think there is still enough left in this wicket."