Tottenham defender Toby Alderweireld has been sidelined for "two or four weeks", according to Jose Mourinho.
Alderweireld pulled up during Spurs’ 2-0 win over Manchester City on Saturday.
As reported by Standard Sport earlier on Wednesday, scans on the muscle injury were inconclusive but there were hopes that the damage was not as bad as initially feared.
“He has a muscular injury but not as big as we initially thought," said Mourinho ahead of Thursday’s Europa League visit of Ludogorets.
“He will have time to be out but not like a month which is what we immediately thought. So I would say between two and four weeks. But of course he is not playing tomorrow.
"Of course [it’s] bad news as he was playing his best football. He is an important player that we miss.
“But we have Davinson Sanchez and not for tomorrow, as he is not in the list, we have Joe Rodon. We fight with what we have.”
Rodon, who replaced Alderweireld for the final ten minutes against City, is ineligible in Europe, while Mourinho said he considers fit-again Japhet Tanganga “more as a full-back" than a centre-half at present.
Alderweireld will now sit out as many as 10 games, with Spurs travelling to Chelsea in the Premier League on Sunday, and facing Arsenal, Liverpool and Leicester City before a Boxing Day trip to Wolves.
A best-case scenario appears to be Alderweireld returning for the final Europa League group game on December 10 as Antwerp visit north London.
Matt Doherty missed the win over City after contracting coronavirus on Republic of Ireland duty but the right-back has returned to training following a negative test, although Mourinho said he did not know if he was ready to start on Thursday.
“It's good because in the Europa League we can have 12 players on the bench so 12 plus 11 makes 23 and it's good to have him in the 23-man squad,” the Spurs manager said of Doherty.
Erik Lamela is continuing to recovery from an achilles problem and is not expected to be available for Ludogorets or Chelsea.
Mourinho said Ben Davies would play against the Bulgarian side and promised to make changes from the win over City.
“I will not play the same team I played against Manchester City,” he said.
"Of course I'm not going to. There are different reasons for that. Of course the accumulation of matches is a problem. The Toby injury has a relation with an accumulation of minutes.
“It's also about players that work a lot. They're not starting matches and they deserve to start. Ben Davies has to start. He didn't play Sunday, he plays tomorrow.”