Tottenham’s Europa Conference League match against Rennes on Thursday is off after eight players and five members of staff tested positive for Covid-19 at the London club.
Their match against Brighton on Sunday in the Premier League is believed to be under review.
Spurs said they closed their first-team training centre on Wednesday.
“Discussions are ongoing with Uefa. We shall provide a further update on this fixture in due course,” the club said.
Speaking earlier on Wednesday, Spurs manager Antonio Conte said: “Now, for sure, we are a bit scared because tomorrow we don’t know what happens.
“Every day, we are having more positives. This is not a good situation.”
In a statement on Wednesday night, Rennes criticised the move, saying they “reserve the right” to appeal against the decision to Uefa.
“This lack of fair play is all the more glaring as Tottenham had confirmed by email that the match would be held at the start of the afternoon before warning Rennes of their intention not to play just after landing in London,” the statement added.
Following Spurs’ league game against Brighton, they face Leicester City on 16 December and Liverpool on 19 December, before an EFL Cup quarter-final against West Ham on 22 December.
“To speak about football today is impossible. The last situation made me very upset,” said Conte.