Atletico Madrid coach Diego Simeone has been charged with improper conduct by UEFA following an incident during the 2-0 Champions League win over Juventus.
UEFA did not confirm what action Simeone is being charged in connection with, but Omnisport understands it relates to the Argentine celebrating Atleti's opener by clutching his crotch while gesticulating to the crowd.
Simeone attracted criticism from some for the gesture but he apologised after the match, explaining it was directed at Atletico fans, showing them "that we have cojones".
"To start [Diego] Costa and Koke after they hadn't played for a month takes balls," he added.
The Argentine admitted that it is not the first time he has performed such a celebration, telling Sky Sport Italia: "I did it as a player in Lazio vs Bologna and I did it again to show our fans that we have cojones. It wasn't aimed at the other team, I was turning towards our own supporters.
"It's not a nice gesture, I'll admit, but I felt the need to do it. It was such a tough game, we fought so hard and Diego Costa worked really hard when he wasn't 100 per cent fit. I had to show what I was feeling.
"I can only apologise if anyone was offended, but I did it from the heart."
Atletico appeared to be heading for a 0-0 draw in Wednesday's round-of-16 first leg at the Wanda Metropolitano, before Jose Gimenez's 78th-minute goal inspired a 2-0 win that was capped off by Diego Godin.
UEFA has also charged Atleti with blocking stairways and the throwing of objects, while Juve are in hot water for a late kick-off.
Juve coach Massimiliano Allegri also has to answer a specific charge himself in relation to the delayed start of the match.
The cases will be dealt with by UEFA on a date yet to be confirmed.
Atletico will face Juventus in Turin for the second-leg of their last-16 tie on March 12.