The on-field conduct of Champions League rivals Barcelona and Chelsea could be investigated, said Lennart Johansson, the president of European football's ruling body.
Johansson, who is aiming to win re-election ahead of French legend Michel Platini next January, said that behaviour on the pitch is a "crucial issue" for the game and has warned players to improve their on-field conduct.
A case in point, he said, was the Barcelona v Chelsea Champions League match in midweek.
Johansson repeated that both clubs should face a disciplinary investigation following their match, despite neither the referee nor match delegate recommending any action be taken.
A UEFA spokesman has admitted that an investigation could still be launched into the conduct of both clubs.
In an interview with the Press Association, Johansson said, "On the crucial issue of behaviour in the game I do think there were issues at the recent Barcelona v Chelsea match which will need to be looked at by the UEFA disciplinary bodies in relation to both clubs.
"It's a matter for the UEFA disciplinary process, not for me personally, but I do want to emphasise the importance of good standards of behaviour and proper conduct in the game.
"This applies to every club, coach and player and it's not my intention to single out any individual.
"Like many in the game I think improving standards of conduct is an important issue which must not be dependent on the disciplinary process."
Barcelona players continually pressurised the referee during the match in the Nou Camp, while Chelsea picked up six of the 10 yellow cards shown in the match.
Five or more cautions leads to an automatic fine of 5,000 pounds but following Johansson's remarks further action could follow against both clubs.
A UEFA spokesman told PA, "Nothing was mentioned by the referee or match delegate and the current state is that there are no disciplinary sanctions.
"That is not to say that things won't change however."
Johansson was in London this week to launch his campaign to be re-elected president for a fifth and final term. He is standing against Platini and UEFA's 52 member associations will each have a vote on January 26.
The Swede, 77 next week, has expressed concerns about club ownership but stressed Friday he is not referring to any individual club.
Johansson is concerned that his remarks about ownership in a press conference in London Thursdau have been interpreted as an attack on Chelsea owner Roman Abramovich.
Johansson said, "As we look across the European football scene it's clear that there are many issues and challenges that have to be faced."
"I have highlighted two of these (player behaviour and club ownership) which are matters for the whole of the game to consider but I do not regard this as a matter for one club or one individual."
"I do have concerns about the future direction of club ownership but we have to be realistic about the realities of the market."
"The important thing is to ensure good corporate governance and financial transparency."
"These should be the aims of every professional football club. I'm saddened if my remarks are used against any individual club because it's not for me to comment on any club compared to another."