UEFA referees' chief Pierluigi Collina says new concussion rules that come into force in the Champions League this week will clear up any doubts about when players are able to continue after suffering a head impact.

The new rules agreed by UEFA and FIFA will affect all matches and give referees the ability to stop games for up to three minutes to allow the team doctor to carry out an on-pitch assessment of the injured player.

Following that assessment, only the team doctor will have the authority to decide whether the player can continue or not.

Collina said: "I am pleased the new procedure in case of concussion will be implemented this week, just a few days after it was approved by UEFA's executive committee.

"In my opinion, the new procedure gives referees a clear view of who makes the final decision on whether a player can continue to play or has to leave the game - it is the team doctor and no-one else. I hope this will lead to improved health and safety of players overall."

The new rules follow several cases last season - notably Uruguay's Alvaro Pereira and Germany's Christoph Kramer at the 2014 World Cup, and Everton's Romelu Lukaku and Tottenham keeper Hugo Lloris in the Premier League - of players carrying on despite suffering head injuries.