Lancashire in control
Lancashire's batsmen broke more records and their bowlers made significant inroads into Northamptonshire's batting as Glen Chapple's side strengthened their grip on the LV= Division One match at 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 in their first innings at 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, who were worn down by the relentless batting of double-centurion Ashwell Prince, who made a career-best 257 not out, and then 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 on a wicket 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 in cricket hit three sixes in four balls off Graeme White and Steven Crook and he went from 37 to 87 in just 22 balls, a T20 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. 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, many of whom bore up well under the pummelling they received. 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 four for 42.