Leicester will take a slender 1-0 lead into the second leg of their Championship play-off semi-final against Watford after David Nugent bagged a late winner at the King Power Stadium on Thursday.
Nugent netted for the first time in 17 matches with eight minutes remaining to give the Foxes a narrow advantage to protect in Sunday's second leg at Vicarage Road.
"It was a tight game, but we were able to take a chance towards the end when it looked as though it was going to end 0-0," Leicester manager Nigel Pearson.
"It's all to play for. We've got to be positive and try and win the next game as well."
Watford boss Gianfranco Zola added: "I didn't expect them to score, I didn't see that coming at any time because it looked like we were in control of it.
"We had a few chances when we should have scored. But it's only half-time. We are looking forward to playing on Sunday."
While Leicester celebrated sneaking into the play-offs on goal difference courtesy of Anthony Knockaert's injury-time winner at Nottingham Forest on Saturday, third placed Watford were left to rue failing to capitalise on Hull's home draw with champions Cardiff.
And the beginning of the match reflected the differing moods as Leicester took the attack to the Hornets in front of a season-high crowd of 29,560.
Nugent flicked a third-minute cross from Lloyd Dyer goal-wards but it lacked the power to beat Manuel Almunia and the former Arsenal goalkeeper, fit again after a hamstring injury, smothered the ball.
Almunia was then in the right place when Ritchie De Laet's near-post header from Matty James' corner stuck in his midriff.
Dyer and Nugent combined again after 27 minutes. This time Leicester's leading scorer made a solid connection but he steered his side-foot effort a yard wide when he really should have broken his long run without a goal.
The visitors had Almunia to thank as they went into half-time all square as the Watford captain blocked Knockaert's near-post shot.
Watford spurned a golden opportunity on the hour mark.
Marco Cassetti's crafted pass with the outside of his foot found Matej Vydra in space on the edge of the box but the Championship's player of the year failed to add to his 20 league goals this season and scuffed his shot tamely at Kasper Schmeichel.
And Nugent made him pay when the former England forward headed home Knockaert's free-kick in the 82nd minute for his 15th goal of the season.