While new boss Mourinho was given an explosive first press conference since taking over at Old Trafford last month, Fellaini was enjoying a cigar and what appeared to be a cocktail with twin brother Mansour and friends.
An onlooker said: “He didn’t look like he had a care in the world.”
Mourinho is not likely to look kindly on the actions of the 6ft 4in midfielder, who has become a polarising figure among supporters of the club.
Bought for £27.5million during the disastrous reign of David Moyes, Fellaini has struggled to impress at Old Trafford.
He started just 12 Premier League games last season and has only 11 goals in all competitions in his three seasons.
Speaking in July 2014 after Jack Wilshere was with a cigarette in Las Vegas, Mourinho slammed the Arsenal midfielder.
