Kent 207 (Blake 89*, Porter 3-51) and 252 for 7 (Northeast 116*, Bopara 3-49) trail Essex 569 (Bopara 94, ten Doeschate 91, Westley 88, Lawrence 82, Rabada 4-118) by 110 runs
Kent captain Sam Northeast summoned a century to deny Essex a Specsavers County Championship win in three days but he is unlikely to prevent them from extending their lead at the top of the second division.
Northeast's hundred followed the efforts by four Essex batsmen who departed within sight of three figures in a total of 569, a county record that eclipsed the 560 century-less innings against Sussex at Leyton in 1933, although on that distant day they declared nine wickets down.
Back in the present, Northeast's dogged resistance took a game that was fast running away from Kent into a fourth day. Northeast had entered Kent's innings shortly before lunch when they were 18 for 2, still 344 runs short of making Essex bat again. By the close he was 116 not out, and Kent had closed the gap to 110.
He belatedly found a batting ally in James Tredwell, and the eighth-wicket pair put on an unbeaten 124 in 39.3 overs to prevent Essex celebrating going back to the top of the Division Two table with a well-deserved day off.
Ravi Bopara took three wickets and a catch during the afternoon to help reduce Kent to 128 for 7, but Essex were unable to press home their advantage in a wicketless evening session.
Chasing 362 to make Essex bat again, Kent lost two wickets in the nine overs they had to negotiate before lunch. Sean Dickson was brilliantly caught at first slip by Alastair Cook, diving like a goalkeeper to his right.
Fabian Cowdrey followed four balls later when he lifted the ball into Dan Lawrence's hands at point to give Jamie Porter his 100th first-class wicket.
It wasn't long before Porter had No 101 when Joe Denly went lbw to one that nipped back to the bowler's second ball after the interval.
Northeast put on 57 with Darren Stevens to carry Kent to the relative safety of 86 for three. But two quick wickets had them deeper in trouble. Stevens was bowled through the gate when Bopara found some late movement.
And Alex Blake, who held together Kent's first innings with an unbeaten 89, went for two caught low down at cover by Bopara to give Quinn a second wicket.
Adam Ball helped Northeast put on 27 for the sixth wicket before he was trapped lbw by Bopara, who then had Callum Jackson caught at mid-on by Quinn.
The captain found an ally in James Tredwell for the eighth wicket and they passed fifty in a little over 15 overs, with Tredwell contributing 34 of them with six firmly-struck boundaries.
Tredwell went to his fifty off 86 balls, with nine fours, as he pushed Ryan ten Doeschate into covers for two. Almost immediately Northeast carved Napier through mid-on for the four that not only brought up his own century but also the hundred partnership.
Northeast's third ton of the season took 172 balls, with 15 fours, while the stand with Tredwell encompassed 28 overs.
Essex gave Kent another hour and a quarter's toil in the field in the morning as they added 85 to their overnight total to post a 362-run lead on first innings. Kent did claim four wickets in the process, but that was scant consolation.
Ten Doeschate became the fourth Essex batsman to depart within sight of a century, and the second in the nervous nineties, when he was beaten for pace by Mitch Claydon to edge behind. His 91 came off 122 balls and with a dozen fours.
Kagiso Rabada had gone wicketless on day two after taking the prize wicket of Cook the previous evening. The South African quick finished with figures of four for 118 from 34 overs. He ended Napier's cameo of 12 in eight balls, with a brute of a delivery that reared up and caught the shoulder of the bat.
Rabada versus Cook had been a highlight of the first evening; Rabada versus Quinn was equally fascinating, though at a lower level. The tail-ender had one edge fall just short of Tredwell at second slip, the next ball flying through the cordon for four. Not surprisingly James Foster protected his young partner in the following over. But Quinn became Rabada's fourth victim, pegged on his back foot lbw.
Foster hoisted Tredwell straight for six, but in an Essex innings where batsmen just failed to reach landmarks, he holed out for 49 to Stevens on the long-off boundary. It should have been a fifty, but Foster had declined a single a ball before in keep Porter away from the strike.