Hugo Lloris suffered an injury early on at White Hart Lane, and the Tottenham stopper looked in bad shape as he left the field on a stretcher.
There were only two minutes on the clock when a combination of Jamie Vardy and Kyle Walker slid into the ex-Lyon shot-stopper.
He appeared to damage his right knee, and was stretchered off without managing to move that leg at all, with Michel Vorm replacing him.
Manager Mauricio Pochettino will be hopeful that the damage won't rule his goalkeeper out for too long, with Spurs not to be action again for two weeks. After the game, he confirmed to reporters that Lloris had gone to hospital with a gash on his knee, with ESPN man Miguel Delaney quoting him as saying it was "a cut on the tendon."
Poch on Lloris: "We don't have news. He's in hospital. We wait for doctor now. We hope nothing big. It's a cut on the tendon."— Miguel Delaney (@MiguelDelaney) March 21, 2015
Tottenham would go on to concede three goals in the match, with the stand-in stopper unable to make much of an impression between the sticks.
Dutchman Vorm was culpable in Tottenham's 2-1 FA Cup defeat to the Foxes in February, failing to stop a Jeffrey Schlupp effort as Leicester knocked the Lilywhites out in the fifth round.
One of the first acts he had to deal with on Saturday was a speculative David Nugent effort after the striker had spotted the former Swansea man off his line, with the 31-year-old only just getting his fingers to the ball.
A lengthy spell out for Lloris would be a catastrophe for Tottenham, with the Frenchman underlining his quality this season on many occasions and proving himself to be one of the world's top goalkeepers.
Despite impressing at Swansea and going to the World Cup with the Netherlands last summer, Vorm hasn't really covered himself in glory in his 11 appearances so far, and the game with Leicester was his Premier League debut for the North Londoners.
Depending on how long Lloris's injury keeps him out, the Dutch international may get a run in the first team, and Spurs fans will be hoping he can show the form he did in South Wales rather than what he has demonstrated in cup games this season.