Uefa is "sure" to investigate the match between Chelsea and Barcelona, says its president Lennart Johansson.
Ten bookings led to players surrounding the referee, who was confronted at the end by Barcelona coach Frank Rijkaard.
"I cannot deny that we have been sleeping by not taking action earlier," said Johansson after the latest stormy Champions League tie between the sides.
"I'm sure now things will happen as it was so obvious and the people we had in place who saw it will report it."
Chelsea can expect a fine because any team picking up five or more bookings in a game is automatically punished.
The size of the fine and any penalty for Rijkaard will depend on the reports of referee Stefano Farina and Uefa match delegate Wolfgang Thierrichetr.
Uefa is keen to stamp out players surrounding the referee during a match and may decide to make an example of both clubs as well as Rijkaard.
"I'm against this behaviour but I don't make the decisions, they are taken by the disciplinary bodies," said Johansson.
Uefa communications director William Gaillard said on Wednesday: "We may open an investigation if there are a large amount of cards, if other incidents are mentioned by the referee or Uefa match delegate or if either team files a complaint.
"We will examine the reports when we receive them and see if there is anything that would lead to an investigation being opened."
Barcelona could also be in trouble after their fans are thought to have hurled bottles at the Chelsea players.
The incident took place when the Premiership side's players applauded the travelling supporters in the top tier of the Nou Camp after the final whistle.
Blues midfielder Frank Lampard said: "I knew things were raining down but none of them hit me.
"There was a bit of banter with the Spanish fans and that was good."