Mauricio Pochettino fears Harry Kane could miss the remainder of the season after suffering another ankle injury in Tottenham's Champions League defeat of Manchester City.
The England captain, who was out for a more than a month after sustaining ligament damage in January, rolled his ankle and was then caught on it by Fabian Delph in the quarter-final first leg.
Spurs went on to win the game 1-0 courtesy of a second-half goal from Son Heung-min.
Spurs boss Pochettino said: "If you see the action it is an action that can damage the ligament again. We need to check in the next few days.
"It is so painful. We hope it is not a big issue and try to recover as soon as possible but it doesn't look good."
Asked if he was worried Kane's season could be over, Pochettino said: "Yes. We need to check tomorrow but it looks the same, a similar issue.
"Very sad, very disappointed, and it's going to be tough for the rest of the season.
"We hope it's not a big issue but there's not much time to recover. He's twisted his ankle and we will see how he reacts in the next few hours."
Pochettino claims City are "still the favourites" ahead of the second leg. "It's going to be tough," he added.
"But we're happy, we showed great quality, our performance was good but there are still 90 minutes to play."
Reflecting on his team's performance, he said: "It was a very good game, we were all excited and motivated to play this type of game.
"The energy was good, fantastic, and the penalty save gave us a big lift. There were so many positive things after a few months when we were so disappointed with some results.
"But with the spirit we play, anything is possible."
Hugo Lloris, who saved a first-half penalty from Sergio Aguero, hailed the victory as "a good win".
Despite losing Kane to injury, Lloris added: "Hopefully, it's not too bad. You know the feeling when one of your best players goes off injured but we stayed strong.
"Lucas (Moura) came on and he gave us fresh energy and helped us to finish the game the right way."
