Nyon - Players on a yellow card will have their bookings voided after the quarter-finals of the Champions League and Europa League, UEFA said on Thursday.
"As of this season, all yellow cards from the beginning of the group stage will expire on completion of the quarter-finals," it said.
"Bookings will therefore not be carried forward to the semi-finals," it added.
UEFA said that it had decided to apply the same rules to its club competitions as those already in place for the European Championship.
The decision was made by its emergency panel, given that the 2014-2015 Champions League and Europa League are already under way.
Previously, players who picked up yellow cards went into semi-final matches knowing one more booking would see them suspended for a possible final.