Arsene Wenger has been hit with a UEFA charge of improper conduct over comments he made about the match referee after Arsenal's UEFA Champions League game against AC Milan on Tuesday.
The Gunners manager was upset with Damir Skomina after the final whistle at Emirates Stadium and confronted the Slovenian official.
Wenger also criticised Skomina in his post-match remarks, saying he had awarded too many decisions to the Italian visitors.
He said: "I was not happy with the referee tonight because I felt he gave many free-kicks in the middle of the park.
"Every time they went down a free-kick was given for them, and they sensed that very quickly and they used it very well."
UEFA later confirmed that Wenger's remarks would be looked into, once Skomina's report had been filed, and it has now been decided that action should be taken.
"A disciplinary case has been opened for improper conduct," said a spokesman for European football's governing body.
If the case is proved and Wenger is given a touchline ban, it will be the third time within the space of a year he has been given such a sanction by UEFA.
UEFA handed Wenger a one-match touchline ban for an on-field rant at Massimo Busacca following his team's last-16 exit to Barcelona last year.
The Arsenal boss was left fuming at the Swiss referee's decision to send off Robin van Persie.
Wenger was then handed a further two-match touchline suspension for violating his Barcelona ban by communicating with the Arsenal bench from the stands during the Gunners' play-off tie against Udinese earlier this season.
The Gunners beat Milan 3-0 in Tuesday's match after Laurent Koscielny, Tomas Rosicky and Van Persie scored in a stunning first-half performance.
However, they could not push on after the interval and bowed out 4-3 on aggregate after their heavy defeat at the San Siro in the first leg.