Middlesex 271 (Harris 61*, Buck 5-54) and 109 for 2 (Malan 55*) trail Northamptonshire 445 by 65 runs
James Harris and Dawid Malan gave Middlesex hope of saving the game at Northampton with fifties at the start and end of the third day. Harris' first-innings 61 not out reduced the deficit to 174 and then, having been asked to follow on, Malan went to the close unbeaten on 55 as Middlesex ended a day of uniform grey cloud 109 for 2, trailing by 65.
Having been dominated for the first two days of the match, Middlesex desperately needed a response and Harris provided one in the morning session. Resuming on 134 for 7, Harris and Toby Roland-Jones finally got to grips with their task and calmly added 59 for the eighth wicket through several back-foot punches and a two very sweet straight drives from Harris.
The Welshman was dropped on 25 - a sharp low chance to Jason Holder's left boot - and then went through to fifty in 92 balls with six fours.
The pair occupied the first hour before Roland-Jones was trapped lbw by Nathan Buck. But Steven Finn made an enterprising, if fortuitous 34, to add another 74 for the ninth wicket before Buck wrapped up the innings four overs after lunch - Finn driving to second slip and No. 11 Tim Murtagh holing out to mid-off - to seal a five-wicket haul.
Not deterred by their horrific collapse here last season, when Northants lost having asked Middlesex to follow-on, Alex Wakely sent the visitors in again and Buck struck twice with the new ball - Nick Gubbins driving to Holder at second slip before Stevie Eskinazi found third slip to fall for a second-ball duck.
At 10 for 2 and still more 150 behind, Middlesex were sliding out of the game but Sam Robson survived numerous plays-and-misses to anchor the innings and Malan found some good touch at the other end. He was particularly fluent after a rain-extended tea where 64 runs came in 13 overs, cutting and driving with purpose to reach his half-century in 60 balls.
The third-wicket stand had added 99 before bad light ended the day 22 overs early. With a showery forecast for the final day, Northants might be concerned about forcing a victory their performance from the first two days has set them up for.