Magnificent half-centuries from tailenders David Willey, Steven Crook and Trent Copeland put Northamptonshire in a dominant position on the second day of their LV= County Championship Division Two match against Essex at Wantage Road.
The final two wickets piled on 228 runs as Northants were eventually bowled out for 399 with Crook unbeaten on 88 off 104 balls and Willey smashing 76 from 78 deliveries.
Australia international Copeland, batting at 11, also bludgeoned a 67-ball 70 as Graham Napier took 6-93 for a bewildered Essex attack.
The visitors began their second innings 216 runs behind but fought back somewhat in the evening to close on 94 for two.
Northants began the day 156 for five, 27 runs behind their opponents with Rob Newton resuming on 35 and James Middlebrook 14.
Neither was able to add to their overnight total, however, as both edged to Essex captain and wicketkeeper James Foster off Napier, completing his eighth five-wicket haul in first-class cricket.
Napier struck yet again when he trapped Northants wicketkeeper David Murphy lbw before Willey and Crook put on a superb 111 to give their side a substantial lead.
Willey raced past 50 off just 58 balls before rain stopped play 13 minutes before lunch was due with the hosts now coasting on 280 for eight.
The delay did not stop Willey and Crook setting a new record ninth-wicket partnership for Northants against Essex.
They went past the 110 delivered by Johan van der Wath and David Wigley at Northampton in 2007, but Willey then holed out by smashing Reece Topley to Rob Quiney at deep fine-leg.
Crook then completed his half-century off 57 deliveries before Copeland hammered his way to the landmark off only 41 balls.
Another county record against Essex tumbled when the final-wicket pair surpassed the 88 David Sales and Michael Davies compiled at Wantage Road in 1999.
A sensational stand was broken on 117 when Copeland launched Tymal Mills and was well caught by Topley at fine-leg.
Essex reached tea on 26 without loss yet the heavens opened again during the interval, leading to a loss of 11 overs and a delayed start to the evening session.
Willey then broke an opening stand of 77 when Tom Westley departed for 38, brilliantly taken by Northants captain Stephen Peters at midwicket.
Ben Foakes went cheaply in the penultimate over as he edged Copeland to Murphy, although opener Quiney remained and will resume on 44 tomorrow.