And Pedro headed in as the Blues ended a five-match losing streak away from home to reach the last four, where they were drawn to face Southampton. Manchester United will meet Tottenham in the other semi-final, with the ties to be played on the weekend of April 21-22.

Antonio Conte's Chelsea succeeded Leicester as Premier League champions last term and also reached the FA Cup final, losing to Arsenal.

The competition represents the Blues' final trophy chance of an at-times tumultuous season after their midweek Champions League exit at Barcelona.

The omens appear good. They had beaten Leicester in all five prior FA Cup meetings and the last three times - in 1997, 2000 and 2012 - they went on to lift the trophy.

Morata was one of three changes for Chelsea, starting for just the second time since the league draw with Leicester on January 13.

Tiemoue Bakayoko was another brought in. The midfielder struggled, regularly relinquishing possession.

N'Golo Kante was there to mop up - and do so much more. Kante seemed spurned on by a smattering of early boos from Leicester supporters with short memories, as he reminded them of his role in their 2015-16 title triumph.

Marc Albrighton fired wide after two minutes and Antonio Rudiger cleared as Wes Morgan threatened at the far post as the hosts went close again.

Willy Caballero - continuing in the cup in place of Thibaut Courtois, who, Conte said, had a minor hamstring problem - saved as Wilfred Ndidi shot from 25 yards.

Next Kasper Schmeichel denied Morata at the other end. The striker's shot was straight at the goalkeeper.

Harry Maguire ran forwards and tried to feed Kalechi Iheanacho, who allowed Andreas Christensen to retrieve the ball uncontested.

Maguire soon found himself defending as Morata rounded him in the right side of the area before hitting the outside of the post from an acute angle.

Chelsea struck on the counter-attack after Marcos Alonso tackled Riyad Mahrez on the edge of the Blues box and Rudiger found Willian.

The Brazilian surged forwards before freeing Morata, who finished with a confidence of which he has been so shorn of late. The strike ended a run of 13 appearances without a goal.

Bakayoko's poor performance, which included a booking, saw him replaced at half-time by Cesc Fabregas.

A Caballero calamity almost presented Leicester with an equaliser, but Mahrez fired well off target after the goalkeeper's poor clearance.

Next Vardy found plenty of space eight yards out, but sent a header from Ndidi's lofted pass well over.

Eden Hazard fired over and Schmeichel diverted a Victor Moses cross away from Morata before Leicester levelled.

Mahrez squeezed in a cross from the right and Chelsea failed to deal with it. Vicente Iborra had two efforts, the second saved by Caballero as far as Vardy, who prodded in.

Vardy was denied by Caballero and Morata by Schmeichel as the match went to extra time.

Chelsea made the breakthrough when Kante crossed and Pedro, on for Willian, rose between Ben Chilwell and Albrighton to head in over Schmeichel.

The visitors defended desperately at times as Leicester pushed for an equaliser to force penalties, but Chelsea held on.

- PA