From the players, to his staff and the vociferous 6,100 travelling support, Coyle felt all combined to create a seismic cup shock.

Cup king Coyle took St Johnstone to the semi-final of the Scottish CIS League Cup in 2006, after a 2-0 win against Rangers at Ibrox, before losing 2-1 to Celtic at Hampden in the Scottish Cup semis the following year.

He then guided Saints to the Challenge Cup Final shortly before taking the reins at Turf Moor, with assistant Sandy Stewart steering the side to a 3-2 success against Dunfermline.

However, defeating the Champions League finalists and Premier League leaders tops those achievements, and Coyle said: "In terms of scalps, they don't come any better than Chelsea.

"To knock them out of the cup, it's certainly going to be the greatest result so far.

"To come to Chelsea, who are in terms of world football one of the elite clubs, to win the game, albeit on penalties, I think it shows you the magnitude and effort the players have put in."

And he felt his positive side ultimately merited their win: "I think we've deserved it.

"I know that sometimes you ride your luck, but at 1-0 down it would have been very easy to feel sorry for ourselves and hide, but nothing could be further from the truth.

"We went down to a quality goal by Drogba.

"But we felt at half-time if we could stay in the game and retain a belief in what we could do we had a real opportunity and that would give us a platform to mount a real challenge in the game.

"We did that, scored a very good goal and could have added to that.

"I said before the game that we'd try to commit players forward at every opportunity.

"It's all very easy to pack 11 men behind the ball and ultimately Chelsea would pick you off and you'd lose one or 2-0. You'd think, 'well, you've only lost 2-0', but you've contributed nothing to the game.

"So I felt when we got a chance we would try to commit players forward and give the fans something to shout about."

Once the game went down to the lottery of penalties, Coyle felt his players had done themselves justice: "Regardless of how the game went and whether we'd won or lost the shoot-out, I would have said the same thing – I'd asked the players to come and make sure that they rewarded the fans with a performance, and they did that.

"I'm not being smart after the event. If we'd have lost it I'd still be saying the same thing.

"Penalties, as we know, sometimes are a bit of a lottery. Sometimes they go for you, sometimes they don't. We're obviously delighted because it gives the town and the football club a bit of prestige involved with being in a cup and going to the quarter-finals.

"Obviously there are the financial rewards from that as well.

"But equally, hopefully it gives everyone in the town a lift."

While his side pulled out all the stops to create indelible memories, the support they received delighted Coyle: "From a population of 70,000, to bring over 6,100 to London, with what's going on with the world economy when money's tight for everybody, to come and give that level of support I'm absolutely thrilled and delighted for them.

"People would have missed a day's work, there's a lot of travel involved and cost.

"The backing we got from 6,100, you'd have thought there was 30,000 there and hopefully it gives everyone in the town a lift."

Burnley kept their heads in a tense penalty shoot-out, although Coyle revealed the players had not prepared for such an eventuality: "All the pressure was on Chelsea – they were expected to win, and win comfortably.

"We'd said if it got to penalty shoot-outs, because I've been there myself and missed a few I know there's a tendancy to change your mind, I asked the players to stay true to where they'd chosen to place the ball and not change their mind; because we knew if they were able to score the goals Brian, we felt, would save a minimum of one. And I'm delighted for him.

"But I'll be honest, we didn't practice them, because who thought it would get to penalties?!

"We know in Graham Alexander we have one of the best penalty takers in football.

"The lads practice a bit every now and then for a bit of fun. Wade Elliott took one at the end of training on Tuesday, off his own back, and it ended up in the same place.

"But when he stepped up I really fancied him to score because I thought he was outstanding. Wayne Bridge is a very good player, but I don't know if he'll come up against many opponents as tricky as Wade Elliott.

"But I think the biggest thing on the night was the team, the effort and the work ethic they showed, being prepared to really cover the grass for each other."

Brian Jensen emerged as the hero, saving two penalties, while Ade Akinbiyi came off the bench to take the game too extra-time, and Coyle said: "Brian has been outstanding all season.

"I'm delighted for him because it's a reward for how hard he's been working in the games and training.

"Aside from scoring the goal, Ade led the line, brought us up the park to get others on the ball, and that was a big turning point in the game.

"Ade's had an unbelievable career and moved for an awful lot of money.

"He's been out of the 16 due to the emergence of young Jay Rodriguez, and he's been nothing but a model professional.

"Every day he's in there, the team spirit's so important to him that even when he's not involved he's there wishing the boys all the best and encouraging them.

"Sometimes you get lucky with substitutions. I just looked at the game and felt Martin Paterson had run his game and we needed a physical presence up there because the two lads at the back are physically strong and Ade is intimidated by no-one."