Alvaro Morata s first goal since Boxing Day on his return to the Chelsea starting line-up put the visitors on course to bounce back from their Champions League elimination at the hands of Barcelona in midweek. The Italian is eager to ensure a transformation of fortunes.
That proved to be the final bit of goal-mouth action of the half as Chelsea held on for the win.
"Last season it was a pity to lose the final, (not) to celebrate the double with the players". Our target is to do our best.
"It wasn't easy to play against Leicester because I think they are a good team with great players and we must pay great attention, especially when we are attacking because they have very good players who attack the space and the defensive line".
But Leicester's Jamie Vardy smashed in from close range to force extra-time.
Son Heung-min is in great form for Tottenham Hotspur. Ian Walton Reuters
The omens appear good. But the most important thing is for us to fight until the end in every competition.
He added: 'The fact we played our home games there this season you would think would be a benefit for us but it is the FA Cup semi-final so it will be hard no matter what'.
Losing the final to London rivals Arsenal last season cost them a Premier League and FA Cup double but they have won the trophy seven times, the last four of them between 2007 and 2012.
For the remainder of the 90 minutes, the game was gradually heading to extra-time in what was a pulsating match. His initial shot had been blocked by Andreas Christensen before Vicente Iborra was denied by Cesar Azpilicueta and then stopper Willy Caballero in the ensuing scramble.