UEFA has relaxed its player registration rules so January signings can play for their new clubs in the Champions League and Europa League.
UEFA says starting next season clubs "may register three new eligible players without any restrictions."
Current rules mean Barcelona cannot select Philippe Coutinho in the Champions League because he played for Liverpool in this season's group stage. And Arsenal cannot select Pierre-Emerick Aubameyang in the Europa League because previous club Borussia Dortmund switched to the same competition's knockout rounds after he played in the Champions League.
UEFA says the change brings its competitions into line with national leagues, which do not limit January signings' right to play.
Also from next season, clubs reaching competition finals can use a 23-player squad instead of 18.
