The West Sussex hosts had never previously beaten top-flight opposition in the FA Cup and Yems admits it is currently difficult to process the extent of the achievement.

He said: "I think this is the biggest club to have been here and to beat Leeds United, in the way that we beat them as well...

"We had a plan, we stuck to it, and (it was) all down to the players, they absolutely deserved everything they got.

"We knew we needed to make it as difficult as we can – don't get caught chasing the ball, don't get mixed up in their game and we did that. We let them have it in front of us and the rest is history.

"It's a big club, isn't it?

"It won't sink in until possibly when you're lying on a beach in the summer and there's people talking about it and you see the reruns of what the club has done and who you beat."

Asked about his game plan, Yems joked: "We went to church this morning, lit a few candles!"

Leeds dominated possession on Sunday afternoon but, aside from a first-half Ian Poveda effort and Rodrigo's penalty appeal, struggled to threaten.

Crawley took control of the tie early in the second period courtesy of Tsaroulla's solo effort – his first senior goal – and a bobbling strike from Nadesan, which caught out former Real Madrid goalkeeper Kiko Casilla.

Defender Tunnicliffe lashed into the roof of the net to put the result beyond doubt with 20 minutes still to play, while substitute Max Watters could have added further gloss to the emphatic scoreline.

Yems initially encouraged his players to go out and celebrate the headline-grabbing win, before remembering the current national lockdown which prevented fans from witnessing it live.

"I got myself in trouble a little bit because I'm telling all the boys go out and enjoy yourself and make the most of it and, of course, you can't go out anywhere," said the 61-year-old, whose in-form team stretched their unbeaten run to 10 games.

"We all get knocks in life and in football, you've got to make the best of the good times because you get a lot more bad times.

"Nothing beats winning, it's the greatest feeling to walk in that dressing room and see everyone happy. And they deserved it as well.

"I don't think there are too many people who can say we were lucky."

Bielsa named a strong line-up for the game, albeit making seven changes to the team who lost 3-0 at Tottenham last weekend.

Leeds' latest humiliation adds to recent cup upsets at the hands of Histon, Newport, Sutton and Rochdale, leaving their Argentinian manager full of "sadness and disappointment".

"We couldn't unbalance them when we attacked. We had the ball for a long period of time but we couldn't do much with it," Bielsa told the BBC.

"In the first half we played better than the opponent and the game was played how we wanted it to be played, even if we didn't create much danger.

"In the second half the game was played how the opponents wanted to play. They did create danger to deserve the goals that they scored.

"The result generates a lot of sadness and disappointment for us.

"It's not a question of surprise, we know the characteristics of their players and the opponents, just like every other opponent."