Rangers backup goalkeeper Andy Firth got short shrift from Celtic stewards as he looked to pass a message to Allan McGregor .
The 23-year-old was despatched by the Light Blues dugout to pass on a message to his team-mate.
But the Rangers man made the mistake of sprinting up to the Celtic end to catch his fellow keeper's attention and was quickly told to get back to his own half of the field.
As Hoops substitute Leigh Griffiths watched on and the Parkhead faithful hurled pelters in his direction, Firth was grabbed by a steward and told in no uncertain terms that he wasn't allowed in that half of the field.
Under Premiership rules "no more than three substitutes from each team shall warm up at any one time in the area designated by the match referee".
In practice this means that each team will be allocated a half of the pitch that their substitutes are allowed to enter.
In addition Firth hadn't actually been named as a substitute so wasn't actually allowed to leave the Rangers technical area.
Firth made his debut for Steven Gerrard 's side in the final game of last season when he came on as an 83rd-minute substitute for Wes Foderingham against Kilmarnock.
He conceded shortly after as Eamonn Brophy converted a penalty and is yet to make an appearance so far this season.
