Matthew Hoggard lit up the second day's play at Grace Road with a magnificent opening spell to put Essex on the rack in their first innings.
County's own first innings had come to an end inside the opening hour of play when they were dismissed for 302.
However, Hoggard – who had not figured for the first team since April due to injury – made rapid in-roads against an Essex batting line-up, which was coming off the back of being dismissed for just 20 by Lancashire in their previous match.
His opening burst of 4-12 in a dozen overs had the visitors struggling on 28-4 before 72 from Mark Pettini and skipper James Foster's 45 not out saw them claw their way to 196-6 at the close of a shower interrupted day.
Leicestershire's position might have been considerably stronger had they been able to take wickets regularly at the other end.
Alex Wyatt deservedly picked up two – that of Pettini five overs from stumps was a vital blow – but there was a lack of penetration elsewhere even if Jigar Naik's off-spin did offer County an element of control.
Hoggard, though, was almost unplayable in conditions which favoured the seamers.
Tom Westley was his first victim, wicketkeeper Niall O'Brien taking a fine one-handed diving catch as the former England man nipped one away from the Essex opener.
Hoggard then removed Nicholas Browne lbw with his next ball and, although Owais Shah denied Hoggard a hat-trick, the County seamer was back among the wickets just a couple of overs later when Naik grabbed a tough gully chance at the second attempt to send Jaik Mickelburgh back to the pavilion.
When Hoggard produced a beauty to clip the top of Shah's off-stump, Leicestershire had claimed four quick wickets and had the control of the game in their own hands.
They were frustrated for the next 25 overs by Pettini and Ryan ten Doeschate.
The Essex pair were to add 85 runs either side of tea before Wyatt cramped the latter for room and Joe Burns managed to hold a very good catch at first slip.
Pettini's first Championship half-century of the season kept County's attack at bay for much of the final session, Foster giving him the support he was looking for as Leicestershire struggled to engineer a late breakthrough.
It eventually came when Wyatt switched to the Bennett End and ducked one into Pettini's pads, trapping him lbw to help County reach the halfway stage of the game with their noses just in front.
The opening exchanges of the day had seen Leicestershire achieve their minimum requirement moving from 268-7 to beyond 300. They claimed a third batting point when Hoggard pulled David Masters to the midwicket boundary for four.
It was, however, Michael Thornely who had steered them to the brink of 300 as he took his overnight 37 to 53 before he was pinned leg before by Graham Napier.
The Essex seamer took all three of the remaining Leicestershire wickets to finish with career-best Championship figures of 7-90.
