As the seconds ticked down to the final whistle with the scores level it was Watford who would have been feeling most grateful for the prospect of a replay. Chesterfield are the best team outside the Football League and looked more than ready for the promotion that seems likely to end their season, and perhaps a couple beyond that, but in the fifth of six added minutes the home side stole it, Tom Dele-Bashiru jinking into the box before poking a low shot past Ryan Boot.

It might have been so different. The home side dominated the final half-hour but Chesterfield were never content only to defend, committing in numbers whenever they sensed an opportunity to attack and causing occasional outbreaks of panic in the Watford defence. In the 84th minute they nearly got their reward, earning a corner that was sent looping deep beyond the far post, headed back across goal by Ash Palmer, and from a wonderful position on the edge of the six-yard box sent over the bar by the substitute Ryan Colclough.

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“What was pleasing was we played our normal game. We didn’t change our style or our philosophy, we nearly did it, doing it our way,” said their assistant manager, Danny Webb. “I wouldn’t say we outplayed them but we gave them a good game, showed a bit of class and did the National League proud.”

Losing, he said, was “a kick in the teeth, a sickener” but the league remains their priority. “This has been a lovely distraction and if we had a replay maybe it would have been an unwelcome distraction,” he said. “In hindsight it might be a good thing.”

From the start, Chesterfield moved the ball with pace and intelligence, closed down space, snapped into challenges. Boot, one of five changes to the team that beat Solihull Moors on New Year’s Day and a veteran of two league games this season, distributed the ball much better than his opposite number, the Austrian international Daniel Bachmann, helping his side spring into attack. They offered style and substance, the latter most notably in the intimidating shape of Ollie Banks, who spent his hour on the pitch in constant battle with Wesley Hoedt, two players with near-identical heights and haircuts who also seemed determined to share shirts.

Chesterfield took the lead in the 28th minute, Ryheem Sheckleford’s impeccable cross making Bachmann an irrelevance and dipping on to the head of Joe Quigley, completely unmarked in the middle of the six-yard box, and were the more convincing and threatening side in the opening half.

Though Watford wasted two clear chances in that period neither was the result of their own incisive play. Neither Yáser Asprilla, after intercepting Branden Horton’s back-pass, nor Ismaël Koné, after robbing Freckleton, managed a convincing shot on goal.

“I just didn’t understand what happened,” Valérien Ismaël, the Watford manager, said of the first half. “It was just a mentality thing, it had nothing to do with quality.

“We needed to raise our level, and we made it in the second half. We expected to do it in the first half and have a comfortable afternoon but the players chose the other way, to make it more complicated.”

Seconds after the restart it nearly became more complicated still, but Banks, having contributed a lovely first-time flick to the build-up, sent his volley too close to Bachmann.

For all that the interval brought a notable increase in Watford’s quality and intensity, allowing them finally to create chances with some regularity, it took another 30 minutes, a triple substitution and a superb header for them to equalise.

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Asprilla, switched to the left flank, sent in an early, out-swinging cross and Mileta Rajovic did well to get in front of Sheckleton and better to deflect the ball just inside the near post. They continued to push, and in the 89th minute Dele-Bashiru’s shot from 20 yards was well saved by Boot, but his most telling intervention was still to come.