Manchester United fans threw objects at Atletico Madrid manager Diego Simeone as he rushed towards the tunnel after his side defeated the Red Devils in the second leg of the Champions League last 16.
The Spanish side won 1-0 (and 2-1 on aggregate) as Renan Lodi headed in the go-ahead goal in the first half on Tuesday.
Red Devils supporters at Old Trafford showed their displeasure by going after Simeone, who escaped harm with his dash out of their sight.
It remains to be seen if UEFA take any action against Manchester United as a result of this.
Manchester United will now turn their attention to the Premier League where they are battling for a top-four spot and Champions League qualification for the next season.