Simon Harmer delivered on the threat that he was always expected to pose in the fourth innings at Chelmsford - April conditions notwithstanding - as Essex completed a stunning turnaround victory to extend their home record to 12 wins and a draw in their last 13 games dating back to 2018.
In a thrilling denouement to a match that had begun with the champions being rolled aside for 96 on an 18-wicket opening day, Essex overcame a first-innings deficit of 163 to win by 44 runs, completing their defence of a stiff but obtainable target of 168 ten minutes before lunch, as Jamie Porter uprooted Matt Salisbury's middle stump to complete their first victory of their twin title defence.
It was an agonising end for Durham, who had made much of the running throughout the contest, but had been unable to turn their ascendancy into outright dominance, thanks to the champions' never-say-die knowhow. And no player better epitomised those traits than Harmer, whose final match figures of 10 for 136 included a final surge of five wickets in 39 balls, as Durham were served notice of the quality that sets apart the best red-ball team in the country.
Resuming on 60 for 3, with Jack Burnham and Scott Borthwick having steadied the ship after a frantic collapse on the third evening, Durham resumed the same quick-slow tempo that had served them well towards the close, Burnham charged with providing his side some impetus while Borthwick focussed more exclusively on survival.
And for the first ten overs of the day, as the pair chipped off a further 23 runs to take the requirement into double figures, Durham's poise was broadly unruffled, even if three consecutive maidens for Harmer was a quiet reminder that Essex would happily drag this chase out all day if their visitors weren't minded to make the running.
Burnham duly did just that - a scamper to the pitch drawing a scuffed drive through long-on as Harmer conceded his first boundary of the day, but two balls later, his aggression would prove to be his undoing. Harmer served up an apparent drag-down, but the ball skidded onto a back-foot swipe rather faster than the batter had bargained for, and Tom Westley at long-on steadied himself for the skier.
At 83 for 4, with Burnham gone for 43, the texture of the contest had altered drastically. Borthwick, now obliged to creep out of his shell while Ned Eckersley got to grips with the contest, climbed into a flowing drive for only the second boundary of his innings, but one ball later, Essex were up in unison for a stumping that, to judge by Adam Wheater's peeved reaction, was marginal to say the least. It mattered not. Harmer's juices were now flowing, and his next ball, from round the wicket, straightened to pin Borthwick on the back foot for 24.
Durham were now in freefall. Eckersley was dropped at short leg before he had scored, but Sam Cook picked up the mood as, one over later, he angled a pad-thwacker into Stuart Poynter's motionless feet to pick off the keeper for a six-ball 1. And when Harmer made it three wickets in 11 balls by nailing Ben Raine in front of off stump, again from round the wicket, Durham had slumped to 91 for 7 and the Eagles were circling like vultures.
Eckersley's initial response was an array of panicked swipes at Cook's waspish line, including a brace of inside-edges past his leg stump, but he showed more poise when Harmer was lining him up, with a thumping sweep and a cultured punch through the covers to exploit the acres of space on the unguarded off side.
He had carried the score past 100 in partnership with Brydon Carse, who came out with a runner after turning his ankle on the third afternoon, but Harmer was not to be denied for long. Some extra turn and bounce into the body extracted a gloved strangle to Dan Lawrence at leg slip, and he made it ten for the match when Carse's uncomplicated thumping gave way to an ambiguous non-stroke on the front foot, and the fourth lbw of the morning.
Eight balls later, Porter had put the seal on a thrilling performance. When Essex last won the Championship (as opposed to the Bob Willis Trophy) in 2019, it was Hampshire who gave them the jolt they required with a first-round innings victory at the Ageas Bowl. It's not impossible that Durham's sterling efforts in this contest will have done something similar. To come through a battle royale of that magnitude is the true mark of champions.
"It isn't often we find our backs against the wall like that," Harmer said afterwards. "What we've achieved over the last four years really gave us the belief we could still win from the position we were in.
"It shows the character of the boys, and shows that we aren't only good when we are ahead but we find ways to win. Essex have what money cannot buy. In situations like yesterday morning, it is about the group of guys and you don't want to let them down."