The Foxes had to win at Nottingham Forest in the league for the first time since 1972 and hope that Bolton did not beat Blackpool if they were to finish in the top six. And that is exactly what happened.
Anthony Knockaert's stoppage-time goal sealed a 3-2 win for Pearson's side as Bolton could only draw 2-2 at home. It is Leicester who will play Watford over two legs in the semi-finals by virtue of a better goal difference than the Trotters.
That dream looked a long way off when Simon Cox put Forest, who themselves could have still finished in the play-offs, ahead after three minutes. Goals from Matty James and Andy King sent the Foxes into half-time ahead.
Elliott Ward levelled things up against at the start of the second half before Knockaert sent the 2,025 travelling fans - and the visiting bench - berserk in celebration.
Pearson said: "The players have to take a lot of credit for dealing with the situation.
"We couldn't have got off to a worse start, but we responded very well and went on to create the best chances of the first half and were deservedly ahead, in my opinion, going into the break.
"It was like a cup final. There was a lot of pressure on the players - for both sides - and I'm really pleased with the way we coped.
"Some of our results coming into this weren't the best, despite feeling that our performances deserved more, but we worked hard to get another opportunity so well done to the players.
"We had an outside chance and we've done what we needed to do in terms of winning our game. That's all we could have done and thankfully we got the help we needed from elsewhere."