Hampshire 92 for 7 (Porter 3-17) trail Essex 360 (Cook 124, Westley 111, Abbott 5-58) by 268 runs
Hampshire went from 18 without loss to 18 for 5 as their batsmen found Essex's opening pair almost unplayable, the ball swinging considerably. It didn't get any better for Hampshire until the sun came out belatedly.
By then Ravi Bopara had chipped in with two wickets in his first over as shell-shocked Hampshire slumped to 92 for 7 at the close, still 119 short of making Essex bat again.
Hampshire's head coach Craig White was perplexed after Hampshire's capitulation. He said: "I thought we bowled well this morning to take eight for a hundred and odd. Then for that to happen I'm just lost for words really. I think there were some decent deliveries and some poor shots, but it is a hard one to analyse.
"I'm still a little bit gobsmacked to be honest. There's certainly a little bit in the pitch. It's dried out a bit and done a little bit more than it did yesterday. There were a lot of play-and-misses yesterday, so it was doing a fair bit, and now it's doing enough and it's tricky."
Liam Dawson sparked the rot when he played an unconvincing forward prod to Porter and got an outside edge to the wicketkeeper. Four balls later, James Vince's middle-stump was sent cartwheeling as he was beaten by Porter's pace.
Quinn then had Michael Carberry lbw offering no shot and next ball Rilee Rossouw was caught low down at mid-on by a diving Neil Wagner. George Bailey gave Porter his third wicket when he shouldered arms to one that nipped back and was bowled.
Bopara replaced Quinn at the River End and had Sean Ervine wafting airily at his first ball. Four balls later Gareth Berg gloved a delivery that reared up nastily to give Adam Wheater his second catch of the over. At that point Hampshire were 34 for 7 and only 14 overs had been bowled. Lewis McManus and Kyle Abbott papered over the cracks with an unbroken eighth-wicket stand of 58.
All this after Essex had lost their last nine wickets for 117 runs with Abbott taking his third five-wicket haul of the Championship season in two brief, but hostile spells either side of lunch.
Hampshire had toiled on day one as Alastair Cook and Tom Westley amassed a record second-wicket partnership of 243. But Abbott finished with 5 for 58 from 30 overs as Essex could only reach 360 and he took his Championship tally this season to 25 wickets at 15.76 each.
He claimed four wickets for 15 runs in 11.4 overs on the day, taking 2 for 10 in seven and a bit overs in the first hour followed by 2 for 5 in four overs immediately post-lunch. Abbott had to carry much of the burden for Hampshire's attack after Fidel Edwards suffered a shoulder injury on the first day that will prevent his participation in the rest of the match. Abbott, though, was up to the task.
He had ended the Cook-Westley partnership with the final ball the evening before, and used the new ball to great effect in the morning. With the third delivery of the 81st over he had Dan Lawrence shuffling across his stumps and to exit lbw.
Cook gave his first chance of an innings that spanned 281 balls when he was dropped by Dawson at third slip. Abbott was unfortunate then, but in his next over he had Cook nibbling at the first two balls before trying to hammer the third square on the offside to give a catch behind. With Berg and Ervine nagging away at the batsmen, Bopara and Wheater managed just 12 runs in a fifth-wicket stand that spanned 10 overs before Berg pinned former Hampshire man Wheater lbw.
Bopara, meanwhile, faced 58 balls before reaching double-figures, though he did straight drive Ervine for the four that took him to 11,000 first-class runs.
But the arrival of Ryan ten Doeschate roused Essex from their slumbers. He lifted Mason Crane's first ball over long-leg for six, and followed it with a four through the covers. He outscored Bopara by two-to-one in a sixth-wicket partnership of 51 that took Essex to a third batting point, a significant increase on the paltry two from their previous three matches.
The stand was broken when Abbott returned to the attack straight after lunch. With his fourth ball he had Bopara injudiciously leaving alone a delivery that swung in and took off stump.
Ten Doeschate followed soon after for a spirited 37 when he was beaten by a fast, swinging delivery from Abbott that uprooted his off-stump. Simon Harmer then went lbw to Berg.
After two lengthy rain breaks either side of tea, which reduced the day's allocation by 20 overs, the remaining two Essex wickets fell inside three overs. Wagner went for a big-hit against Crane and was caught on the midwicket boundary before Quinn's fun was ended when Dawson had him plumb lbw. It was a prelude to what was to follow.