Surrey 399 and 253 for 7 (Burns 57, Harmer 4-75) lead Essex 435 (ten Doeschate 168*, Bopara 64) by 217 runs
Simon Harmer and Jamie Porter took seven wickets between them as Essex seized control of their Specsavers County Championship Division One match against Surrey at Guildford on a fascinating third day.
By stumps Surrey were 253 for 7 in their second innings, a lead of 217, after Essex had earlier earned themselves a slender first innings advantage with Ryan ten Doeschate finishing up on a brilliant 168 not out as they replied with 435 to Surrey's 399.
Off spinner Harmer took 4 for 75 from 34 skilful overs and Porter claimed 3 for 48 from 18 overs while Ben Foakes, with a cool and calm 46 not out, again impressed with the bat for Surrey.
Essex captain ten Doeschate, unbeaten on 120 when Essex began day three on 376 for 7, guided his side past 400 and maximum batting points and, eventually, a hard-fought first innings lead of 36.
Those runs looked doubly valuable as Porter and Harmer, in their contrasting bowling styles, built up the pressure on a Surrey team who knew they would have to bat for at least three full sessions if they were to make an Essex final day run chase a tough challenge.
The loss of Mark Stoneman in the third over did not help their cause. Stoneman, who had batted so beautifully first time around for 197, looked like a man in prime form as he almost dismissively twice clipped Neil Wagner's slippery left-arm seamers to the mid wicket ropes in front of the beer tent. Then, however, on 10, he edged the probing Porter to second slip where Harmer juggled the ball for Alastair Cook, at first slip, to complete the catch.
A second wicket stand of 93 between Rory Burns and Scott Borthwick rallied Surrey, but then Borthwick dragged Harmer's off spin to mid wicket to go for 36.
Burns reached a solid 57 from 128 balls, with eight fours, before Porter had him caught behind and Kumar Sangakkara eased to 26 - going past 900 championship runs for the season in the process - only for Harmer to remove him with a classical piece of off break bowling from around the wicket, drawing the great Sri Lankan defensively forward and thin-edging to James Foster behind the stumps.
Dominic Sibley, on 28, was lbw half-forward to a Porter delivery angled in to his pads but also seeming to keep a little low and, with Matt Quinn unable to bowl again in the match because of a back spasm sustained on the first day, the 24-year-old Porter's stamina and willingness to run in for lengthy spells was crucial to Essex's ability to keep their opponents under pressure as a blustery but sunny day wore on.
Harmer, a 28-year-old Kolpak winter signing who has played five Tests for South Africa, then tilted the match further Essex's way by grabbing the wickets of both Sam Curran and Gareth Batty before the close.
Curran, on 4, was athletically caught above his head at short extra cover by leaping substitute fielder Callum Taylor and Batty, who got to 19 without ever suggesting permanency, was well caught by a diving Dan Lawrence at short leg.
Earlier in the day Wagner went from his overnight 20 to 34 while stretching an eighth wicket partnership with Ten Doeschate to 72 before he was caught at the wicket off Curran.
Porter then stayed long enough to help ten Doeschate secure maximum batting points before being bowled by Stuart Meaker for 6, and last man Quinn lost his middle stump to Ravi Rampaul. Ten Doeschate's superb innings, his 26th first-class ton, came from 209 balls and the 36-year-old hit a six and 25 fours.