The striker was injured in a clash with Fabian Delph, and was unable to put any pressure on his ankle after the challenge
Tottenham manager Mauricio Pochettino has admitted that striker Harry Kane could be out for the rest of the season.
Kane had to be removed from Tuesday's Champions League match against Manchester City with a left ankle injury.
In the 55th minute, the Spurs star attempted to block a clearance by Fabian Delph and the City defender inadvertently stepped on Kane's ankle as he was following through.
Kane immediately had to be helped down the tunnel, unable to put any pressure on his troublesome left ankle.
The Tottenham star was replaced by Lucas Moura, with the Brazilian coming off the bench in the 58th minute of a scoreless quarter-final first leg.
Spurs went on to win the match 1-0, getting a 78th-minute goal from Son Heung-Min to give them the advantage ahead of the second leg.
But the win came at a cost, as the Spurs boss said after the game that Kane may have played his last match this season.
"It's very, very sad. It's going to be tough and we're going to miss him - maybe for the rest of the season," Pochettino told BT Sport.
Kane's injury will be a major worry for Tottenham and for England, as the striker injured the same left ankle that he hurt back in January.
Kane was out for six weeks after suffering torn ankle ligaments in a loss to Manchester United on January 13.
With the calendar having shifted to April, Kane appears to be facing a difficult comeback to make it back before the end of the season.
Spurs have six Premier League matches remaining, with Mauricio Pochettino's side holding onto the fourth and final Champions League spot, one point ahead of fifth-placed