Neil Dexter's fine all-round form continued as he struck a career best 163 not out to take Middlesex to within striking distance of victory over a struggling Northamptonshire.
Dexter's first-class highest score - on the back of his best ever bowling figures of 6/63 in Middlesex's last LV= County Championship match - helped the visitors reach 543/7 declared, a lead of 260 on first innings.
After Chris Rogers made a century on the second day, Dexter and Joe Denly - who made his first significant score of the summer - took the game beyond Northants.
Toby Roland-Jones then followed-up his six-wicket bowling efforts in the first innings by smashing 60 from just 30 balls as Rogers' side romped towards a declaration, an innings which included five fours and four sixes.
The seamer then continued his remarkable all-round match by dismissing the Northants skipper and batting lynchpin Stephen Peters for just 10 as the Steelbacks fell to 88/4 at the close, leaving themselves a mountain to climb in order to force a result on the final day.
Day three highlights