A limit in the amount of non-European players in a squad has been lifted as part of a host of changes for the postponed knock-out stages of this season's European club competitions, tournament organisers announced on Tuesday.
Before competition resumes on September 18, clubs will also be able to register as big of a squad as they wish.
Additionally, players who have switched clubs during the summer including Fiji's Semi Radradra who joined Bristol Bears from Bordeaux-Begles, will be able to feature for their new teams.
Radradra's Bears host Welsh region the Dragons in the Challenge Cup last eight on September 18.
The Champions Cup resumes on September 19 with holders Saracens playing at Leinster on September 19 in the first quarter-final.
"The 16 clubs which have qualified for the quarter-finals will be required to register their squads on or before Tuesday 1 September and to ensure that clubs are able to select the strongest possible match day squads in the current circumstances, there will be no limit to the number of players they can register," European Professional Club Rugby said.
The quarter-finals, re-scheduled due to the coronavirus pandemic, will be held on the weekend of September 18-20, the semi-finals a week later and the finals at a yet to be confirmed location on October 16-18.