Since the competition changed to a 14-match group stage in 2014, no team has ever qualified for the quarter-finals of the T20 Blast winning as few as five games, but a combination of bad weather and a miraculous set of results have seen Essex manage just that.

They go into Wednesday's quarter-final at Chester-le-Street against Lancashire as outsiders - not least with Mohammad Amir missing having returned to Pakistan - but after three wins and a tie in their last four games, are confident of causing an upset.

Before Friday's win against Kent, captain Simon Harmer told ESPNcricinfo that the tournament had been "frustrating and challenging" for his side, as he tried to "slowly change the mindset and get players to buy in".

One man who he has struggled to convince of his methods is Ravi Bopara, who missed two games earlier in the tournament after what he labelled "some very tough conversations" about his batting position.

Of Bopara's 141 innings in T20 cricket for Essex, only 17 have come at number six of lower, and eight of those have been in this year's competition.

"It's probably why I got left out in those couple of games earlier in the tournament," Bopara said. "And if I'm brutally honest, I'm still not happy down there.

"But, it's the role I've been given, I'll give my very best, and hopefully we'll win games - that's all I can do."

If Bopara is unconvinced of the logic behind the call - and after liking a tweet from his agent saying "surely you want your best players to face more deliveries", it seems clear that he is - then it has certainly paid off thus far.

His strike-rate 10 balls into an innings over the past three seasons for Essex is only 112.92, but unbeaten knocks of 70 off 35 and 47 off 27 in the must-win games against Surrey and Kent last week demonstrated his ability to 'catch up' after slow starts. Ultimately, those innings were what dragged them through to the knockouts.

And since 2017, Bopara's record for Essex suggests that he is much more effective against seamers than against spinners: he has scored at 9.80 runs per over against pace, compared to 7.43 against spin in that time period, lending support to the idea that holding him back for the end of an innings works as a plan.

Wednesday's quarter-final may prove different. Lancashire have been happy to hold their spinners back until the end of an innings, bowling almost as many overs of spin (22.4) as seam (23.5) at the death.

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Outside of the powerplay, Lancashire's spinners have bowled almost twice as much as their seamers (88.4 overs to 47.5), suggesting that Dan Lawrence - who has averaged over 50 while scoring at more than 10 an over against spin in the past two seasons - is the key man.

"The way Dan's played in this competition - he's been a great find," said Bopara. "We know that he's been around for a while, and we've known that he's a good player, but I just feel that this year, he's kind of nailed it - he's come good.

"He's a strong, powerful guy now - he's filling out, so he's able to strike the ball a bit harder, he's full of confidence and that's great to see. He's played a crucial part in our qualification."

If it is less than ideal for their fans, who are tasked with a 275-mile round trip on a work night, then Lancashire's venue switch to Chester-le-Street should be perfect for their gameplan. Durham's home games this season have, as usual, been characterised by low scores due to a slow wicket and vast square boundaries, and with Matt Parkinson, Liam Livingstone, Glenn Maxwell and Steven Croft in their side, Lancashire will be more than happy to strangle Essex with spin.

But Essex themselves have plenty of pace-off options: between Harmer, Bopara, Adam Zampa and even Cameron Delport, they could bowl as many as 16 overs of spin and medium-pace. It might not be a high-scoring thriller for the neutrals, but it promises to be filled with the tactical nuances that often define modern T20s.

Zampa - after an underwhelming World Cup - has had a solid tournament, taking 12 wickets with an economy of 8.02, despite playing his home games on the competition's fastest-scoring ground, and Harmer suggested that he is a perfect overseas signing.

"He's an intricate creature," Harmer said. "He's very different but he brings a lot of energy. He's a hell of a good guy, always there for you when you need him, on and off the field.

"You can throw Zamps the ball [in the] first six, at the death, in the middle - it doesn't matter, he's always up for it. As a captain, it's been really nice having him in the XI."

It is important to remember why Lancashire are favourites. Nobody in their batting lineup has passed 300 runs in the tournament, but any side boasting the mercurial talents of Maxwell, Croft and Livingstone - not least with the competition's leading wicket-taker in Parkinson to back them up - should win substantially more often than it loses.

But despite Bopara's frustrations, Essex have stumbled across a formula that has started to work for them; if they can bring that into Wednesday's game, they are not to be written off.

Matt Roller is an assistant editor at ESPNcricinfo. He tweets at @mroller98