Players signed in the January transfer window will not be available to play in the Champions League until after the league phase of the competition.
Clubs can only register a maximum of three new players to their squad once the league phase is over by the deadline of Thursday, 5 February.
The same rules also apply in the Europa League and Conference League.
Competing Champions League teams still have two league phase games left before the knockout rounds begin in February.
It means Manchester City will be without Antoine Semenyo and potentially Marc Guehi, if he completes his move, for Tuesday’s trip to Bodo/Glimt and their final league phase match against Turkish side Galatasaray.
New Tottenham addition Conor Gallagher will also be unavailable to Thomas Frank against Borussia Dortmund and Eintracht Frankfurt.
City’s Max Alleyne will however be eligible to play in the competition, despite being recalled from a loan spell at Championship side Watford in January.
Champions League clubs must register a List A squad which is comprised of 25 first-team players and at least eight ‘locally trained players’ before the league phase starts.
However, Alleyne is eligible for List B, a secondary squad made up of youth players born after 1 January 2004.
He meets the criteria as he is 20 years old and has spent three consecutive years at City with a maximum of one loan move inside his association lasting no longer than one year.
Uefa phased out the cup-tied rule for the Champions League ahead of the 2018-19 campaign, allowing players to feature for two different clubs in the competition in the same season.
Paris St-Germain signed Khvicha Kvaratskhelia from fellow European side Napoli last January, and the Georgian winger helped the Parisians win the competition for the first time.
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