Ange Postecoglou has confirmed Lucas Bergvall will miss the rest of the season and admitted James Maddison's knee injury is a cause for concern.
Maddison will undergo scans after limping out of Tottenham's 3-1 win in the first leg of the Europa League semi-final against Bodo/Glimt of Norway on Thursday.
Bergvall, 19, who signed a new Spurs contract earlier in the week tying him to the club until 2031, damaged ankle ligaments in an innocuous incident training ahead of the same game.
'The injury is probably significant enough to keep him out for the remainder of the season,' said Postecoglou.
'It wasn't a tackle, he was on his own, he just went to turn and just his ankle gave away, so it's just one of those things. I've no doubt he'll come back stronger.'
The Spurs boss was more positive about Dominic Solanke, who also came off against Bodo feeling a tweak in a thigh muscle.
'Dom is not too bad, still sore from last night but we don't think it's anything too serious,' said Postecoglou, who promised changes to the team at West Ham on Sunday, with the second leg of the semi-final coming just four days later.
'We'll make changes,' he said. 'We want to put in a strong performance, also give some players a rest and also get some players up to speed because who knows who we're going to need for next Thursday night.
'There's no doubt when you're making seven, eight or nine changes that I make, that has an effect on the team in the Premier League because you're usually playing against teams that are rested and settled, and it's a massive ask, but I think it's been necessary.
'It's painful, unfortunately, but hopefully we get to reap the rewards of that.'