Essex 217 and 195 for 2 (Walter 118, Elgar 60*) lead Surrey 279 (Curran 70, Clark 54, Patterson 51, Rajitha 5-87) by 133 runs
A superb opening stand of 188 between
Paul Walter and
Dean Elgar stunned champions Surrey at the Kia Oval after they had looked to be in control of the Rothesay County Championship fixture.
Walter was the main aggressor, hitting 19 fours in his 118, and former South Africa opener Elgar, though never comfortable at the crease, simply used all his experience to scrap his way his 60 not out from159 balls.
By stumps, Essex were 195 for two in their second innings - 133 runs in front - with Nathan Smith removing both Walter and nightwatchman Simon Harmer, for a duck, in the closing overs.
Surrey had themselves been rallied earlier on an absorbing second day by
Sam Curran's classy 70 and Jordan Clark's 54 in an eighth wicket stand of 82 in 14 overs. That partnership not only rescued Surrey from the depths of 144 for seven, in reply to Essex's first innings 217, but was also instrumental in earning them an eventual half-way lead of 62.
Walter and Elgar's subsequent heroics, however, leaves the match intriguingly poised with two days left. Walter, 31 next week, looked surprised when he was given out caught behind slashing at a widish ball from Smith but his fourth first-class hundred was a wonderful effort.
Elgar, by contrast, remained unbeaten despite several close calls. On 33, just after tea, he edged Smith clean between first and second slips for four to bring up Essex's 100. Neither fielder moved, while later in the final session Elgar survived two impassioned appeals for caught behind and also edged Curran just short of second slip.
Kasun Rajitha, the Sri Lankan Test seamer, was another Essex second day hero, taking five for 87, his best figures of the season so far, but it was the batting of Walter and Elgar that has perhaps tilted this game back towards the visitors.
Using all six of their frontline pace bowlers, Surrey tried everything to break the Walter-Elgar partnership - and Dan Worrall in particular bowled without luck in an excellent eight-over spell immediately after tea - but the two left-handers stood firm until Smith broke through in the 50th over of the innings.
The day began with Surrey, on 94 for three overnight, slumping to 144 for seven before Curran and Clark pulled the innings around with a stand of increasing authority.
And, when Curran pulled once too often at Rajitha - the legside field featuring both an inner and outer ring, placed there specifically to punish any miscued stroke - Smith arrived to help Clark make sure of a batting bonus point.
Brought on for only his third over, strangely late in the innings at 250 for eight, off spinner Simon Harmer soon dismissed Clark for 54 when Elgar at slip did brilliantly to knock up an edged cut and complete a fine reflex catch from the rebound.
And, having seen last man Worrall drive his first ball high into the pavilion for six, Harmer was also swiped over extra cover for four by the Surrey fast bowler before snaring him for 13 courtesy of a more straightforward catch at slip by Elgar.
Smith, who hit one memorable off-driven four off Rajitha, batted well for his 24 not out to underline the New Zealand international's all-rounder status.
Rajitha had earlier made the initial inroads by seeing Dom Sibley edge to first slip, dismissed for a determined 41, and then pin Ben Foakes lbw for two with one that just moved enough back into the right-hander off the seam as he pushed forward.
Shane Snater then defeated an ambitious whip-drive to leg by Jason Roy, who succeeded only in thin-edging the seventh ball he had faced to send his middle stump cartwheeling, while Jamie Overton also departed for a duck when edging a loose drive at the persevering Rajitha.
Curran, however, pulling profitably, on-driving Jamie Porter for one magnificent four and producing a number of sweetly-timed offside strokes off both the front and back foot, moved serenely to his half-century from 64 balls.
Clark, settling in quickly and scoring at a run a ball with some powerful driving punctuating an otherwise watchful defence, provided Curran with the support he needed to push Surrey up to and then beyond Essex's first innings total.
Between them, indeed, the batting efforts of Curran, Clark, Smith and Worrall had turned a precarious Surrey position into a mid-match advantage. That was soon negated by Walter and Elgar, but this game could still go either way.