Lancashire's batsmen broke more records and their bowlers made significant inroads into Northamptonshire's batting order as Glen Chapple's men strengthened their grip on the LV= County Championship Division One match at Emirates Old Trafford.
Replying to the home side's 650 for six declared, the eighth biggest total in Lancashire's history, Northants were 113 for seven at the close of play and now seem to have merely a mathematical chance of avoiding the follow-on target of 501.
This was another depressing day for Stephen Peters' side. They were worn down by the relentless batting of double-centurion Ashwell Prince, who made a career-best 257 not out, and torn apart by the attacking strokeplay of Jos Buttler and Tom Smith.
The visitors' batting then proved itself incapable of resisting a Lancashire attack led by Chapple, who claimed four wickets - taking him to 900 championship wickets - on a surface offering a little extra bounce from the Pavilion End.
In the first half of the day Lancashire extended their overnight 384 well into the afternoon session before Chapple declared, effectively requiring Northants to bat two-and-a-half days to save the game.
Prince's 500-minute innings was the second double-hundred of his career, as well as being the 14th highest score by a Lancashire batsman in the county's history and the biggest since John Crawley made 280 not out, also against Northants at Old Trafford, in 2001.
However, the highlight of the morning session was the clean hitting of Buttler, who scored a further 74 runs off 67 balls before he was caught behind by Ben Duckett off Andrew Hall for 87.
England's limited-overs wicketkeeper hit three sixes in four balls off Graeme White and Steven Crook and he went from 37 to 87 in just 22 balls, a Twenty20 rate of progress.
Striking the ball straight down the ground with enormous power and deploying a variety of reverse sweeps, Buttler could not be contained by the Northants bowlers until Hall moved one off the seam in 114th over of the innings.
— Lancashire CCC (@LancsCCC) June 23, 2014
His fifth-wicket stand with Prince yielded 138 runs in 24.5 overs and Lancashire scored 174 runs in the morning session.
Even then, the suffering did not end for Peters' attack. Smith made 79 and joined Prince in a stand of 140 for the sixth wicket, the third successive century stand of the innings.
Northamptonshire's reply could scarcely have got off to a worse start as Peters was brilliantly caught in the gully by Usman Khawaja off the third ball of the innings and James Middlebrook edged to Smith at slip, both openers falling to Chapple without scoring.
Matthew Spriegel then top-edged Simon Kerrigan to Buttler for 14 and Smith removed Rob Newton and Ben Duckett in the space of three balls, Newton chopping on and Duckett edging to Prince at slip. That left Northants on 54 for five but Richard Levi and Hall then provided the only prolonged resistance with a stand of 44.
However, Chapple claimed the wicket of Levi for 59 and then removed David Willey for two, both batsmen being caught at short leg by Alex Davies. The Lancashire captain finished the day with figures of 4-42.
Northants coach David Ripley conceded his side had been given the run around.
"Once people have got a sniff of victory against us in this division they have been pretty ruthless," he said.
"Lancashire were ruthless with the bat and then came hard at us with the ball. At 40-years-old Glen Chapple produced a phenomenal spell to be running in and causing trouble with short balls. They've just been much better than us and we hope we can learn from that."
Prince said: "The most important thing is it has been a great day for the team to get them seven down after putting a massive score on the board. The bowlers could have been forgiven for thinking it would be hard work after we got a big score, but they put in a great effort."