Essex 191 (ten Doeschate 73, J Overton 3-40) and 147 for 1 (Browne 75*) need 189 more runs to beat Somerset 324 (Trescothick 95, Abell 70, Siddle 5-80) and 202 (Harmer 4-69) by 165 runs
It is no exaggeration to say that the final innings of this game may prove season-defining for both Somerset and Essex.
Surrey will stay at least 16 points clear at the top of Division One regardless of results this round, and while the title will not be won tomorrow, defeat here would effectively rule Essex out of the race. A loss at Taunton would leave them at least 62 points in arrears of Surrey, and tasked with making the highest total of the game on a turning pitch against Dom Bess and Jack Leach, even the most optimistic of fans must have thought victory was unlikely going into day three.
But Nick Browne and Tom Westley's unbeaten stand of 89 means that they are well placed in pursuit of a seemingly improbable 336, with 147 of those runs knocked off and nine wickets in hand, after fighting their way back into the game in the first two sessions.
As Middlesex found out last year when their title defence ended in relegation, defending the Championship pennant is a tough ask. Indeed, even if Essex win here, the odds will be stacked against them. But with table-topping Surrey still to play twice, they will hope to have control over their own destiny.
To put this chase into perspective, Essex have only made one score higher than their final-innings target here all season: while it was their bowling attack, spearheaded by Jamie Porter and Simon Harmer, that won them the title last season, a faltering batting line-up has been the main concern this campaign.
Only twice has an Essex batsman made a Championship hundred this year, and both of those came in the same innings of 517 for 5 during the bore draw between these sides in June. Westley and Varun Chopra are both yet to make a 50; Dan Lawrence is averaging 21.
But here, Westley and Browne were patient, leaving the ball well and picking off several loose deliveries from Bess and Jamie Overton. Leach fought hard, finding considerable turn on a surface that has given encouragement to both sides' bowlers, but Browne and Westley were resolute. Their partnership is yet to prove match-winning, but it has left the game in the balance going into the final day.
It seems much longer than a year since Westley was being worked over by West Indies' seamers in an England shirt, and he has had a wretched run with the bat since; a 49 in the season opener against Lancashire is his best in the Championship to date, and he was bowled without scoring in the first innings, shouldering arms to a Josh Davey inswinger.
While an England recall is more or less out of the question, the signs were encouraging for Essex that he may finally have found the sort of form that brought him to the selectors' attention in the first place.
Both Westley and Browne are beneficiaries of several weeks away from the T20 side; Browne has not played a white-ball game this year, while Westley was left out with an eye on the Championship run-in once Essex's early exit was confirmed. That move looks to be paying dividends.
Earlier, Somerset must have hoped either to take the game away from Essex, or, failing that, to grind them into the dirt. In the end, they did neither, but set a total that looked like it would be too big for Essex.
Numbers two through nine all reached double figures, but Eddie Byrom's 42 was the highest score. For Byrom, a 21-year-old opening batsman in his first full season at Somerset, this felt like an opportunity to press on after a year of fits and starts, but he was pinned lbw by Harmer eight runs short of a third 50 of the season.
Harmer was, unsurprisingly, the pick of the Essex attack on a pitch that has turned from the first morning. When he ripped one past Byrom's defensive prod in his first over of the day, it felt inevitable that Bess and Leach would play a big role in deciding the course of the game. Indeed they still may, but for the first time this week, Essex have their noses in front.