Jose Mourinho said on Friday he was expecting "bad news" on Harry Kane's hamstring injury after the England captain limped out of the 1-0 defeat at Southampton on New Year's Day.
The Tottenham boss said the full extent of the problem would soon become apparent.
Kane pulled up as he slotted home Christian Eriksen's free-kick 15 minutes from time on Wednesday but was flagged offside.
"I don't know yet, I think maybe later today we have news," Mourinho said. "But if you ask me just my feeling, good news or bad news, I am more bad news than good news, what the player felt, Harry Kane leaving a match the way he did.
"He didn't think twice, didn't take him two seconds to realise the severity of the situation."
Spurs, who are sixth in the Premier League, face Championship side Middlesbrough in the FA Cup third round on Sunday.
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