Josh Bohannon became the competition’s leading runscorer as Lancashire as Northamptonshire’s bowlers were made to work in the September heat.
The 26-year-old hit 175, his highest knock of the season and a third successive hundred against Northamptonshire, becoming the second Division One player to pass 1,000 runs this summer in the process.
Bohannon batted almost the entire day, sharing a partnership of 150 with George Balderson – a Red Rose record against Northamptonshire – to guide the visitors to 392 for seven in their first innings, a lead of 160.
Northamptonshire toiled resolutely in the heat for little reward, with seamer Jack White the pick of their bowlers with three for 79.
Having steered his side to 54 for two the previous evening, nightwatchman Will Williams took an early boundary off Ben Sanderson before the Northamptonshire seamer removed him with a rising delivery he could only fend to second slip.
At the other end, White found both movement and bounce, ensuring a difficult start for Williams’ replacement Phil Salt as a couple of balls zipped past the bat and another flew off his inside edge just past the stumps.
Salt had more joy against Tom Taylor, who offered too much width and was punished with three boundaries in a single over – but Taylor eventually got his man when he top-edged a pull and Emilio Gay ran back from his position in the slips to gather the catch.
Taylor was unlucky not to add a second wicket when his very strong leg before appeal against Vilas, on 10, was turned down to the surprise of most and the former Lancashire captain took advantage of that let-off to build a partnership of 92 with Bohannon.
Bohannon’s 50 arrived when he glanced White for three and the Lancashire batter continued to look untroubled after lunch, aside from a rare lapse when he was fortunate to get away with edging Taylor between second and third slip.
White raised the prospect of a slender first-innings lead for Northamptonshire, striking twice in three deliveries as Vilas chopped onto his leg stump for 37 before George Bell was pinned in front without scoring.
But Bohannon remained unruffled at the other end, drilling Rob Keogh sweetly to the cover boundary to advance to 99 before cutting the next delivery, the 184th of his innings, for a significant single.
He raised personal and team landmarks in style soon afterwards, crashing Keogh for six over long-on to move past 1,000 runs for the season and lift Lancashire beyond the home side’s first innings total of 232.
Bohannon found a new ally in Balderson, who was quick to pounce on anything wide of off stump as the pair put together a century stand and extended the Red Rose advantage into three figures.
A thumping cover drive off Sanderson scuttled over the rope to take Bohannon past 150 as he dominated the post-tea scoring, with Balderson adopting a more watchful approach en route to his half-century.
Taylor finally separated the pair by having Bohannon caught behind off a bottom edge, but Balderson, who finished unbeaten on 83, ensured there was no respite for the home side as he and Tom Hartley added a further 53 by stumps.