Alastair Cook stood between Hampshire and a rout as Essex teetered on 72-5 in reply to the visitors' modest 197 all out at in the division two match at Chelmsford.
The England captain will resume on 25 not out after watching his side collapse from the bowler's end, and will set about eating into Hampshire's lead on Tuesday morning.
David Masters was chief destroyer for Essex with 4-29 as they bowled their opponents out in 65.5 overs, Sean Ervine (60) making a battling half-century.
Jimmy Adams, a double-century maker in the previous game against Worcestershire, struggled to make an impact and spent 54 minutes accumulating 11 runs before an edge finished up in the gloves of James Foster.
Either side of Adams' dismissal, Masters trapped Liam Dawson, lbw, and George Bailey who nicked a delivery onto his pad and watched it loop up to Mark Pettini in the slips.
A recovery was led by James Vince and Ervine after some of the early fire had disappeared from the pitch. A few loose deliveries from Masters's colleagues also helped their cause as they put on 82 in 23 overs.
The stand was broken when a full-length delivery from medium paceman Ravi Bopara removed Vince leg before for 43. Ervine was eventually eighth out for 60, that included eight fours and spanned 113 balls, when an attempted stroke off his hips presented Topley with an easy return catch.
After Hampshire had fallen three runs short of securing a bonus point, Essex openers Cook and Tom Westley made a slow but confident start before they were separated in the cruelest of manners.
With the total on 26 in the 14th over, Cook struck a firm straight drive against James Tomlinson which deflected off the bowler's hand and on to the stumps with Westley out of his ground backing up.
But worse was to come when Rob Quiney, Ravi Bopara, night-watchman Masters and Mark Pettini all departed with 52 on the board, Ben Foakes digging in to add 20 with Cook before stumps.