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.”
Following the game against Brighton, Tottenham face Leicester City on 16 December and Liverpool on 19 December in the top flight, prior to 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 the Italian.
“The situation is serious. There is a big infection.”
Conte, who said he had been vaccinated, did not say if the positive cases at the club were caused by the new Omicron Covid-19 variant.
On the state of vaccination among his squad, he said: “I think everyone takes [their own] best decision and is a question for the medical department about people as to whether they are vaccinated or not.”
Last season, Newcastle United’s game at Aston Villa in the Premier League was postponedfollowing a “significant increase” in Covid-19 cases at the Magpies’ training ground.
Later that month, a coronavirus outbreak at Manchester City caused their Premier League match at Everton to be postponed four hours before kick-off.
Villa also had a Covid-19 outbreak in January, which meant no first-team players were available for an FA Cup third-round defeat by Liverpool, while Premier League games against Everton and Tottenham were then rescheduled.