Henrikh Mkhitaryan will not be able to wear the number seven shirt for the remainder of Arsenal's Europa League campaign.
The Armenian international will occupy the number vacated by opposite number Alexis Sanchez, who swapped places with Mkhitaryan at Manchester United on Monday, after he completed his own move to the Emirates during domestic encounters.
However, the club's official site has revealed that he will have to wear a different jersey number when the Gunners face off against different opponents on the continental stage, due to Sanchez's wearing of the number seven during September's clash with FC Cologne.
(You may also be interested in Arsenal Agree Terms With Aubameyang But Dortmund Stall in Search for Replacement)
UEFA rules stipulate that Mkhitaryan will have to be assigned a new number if and when he features for Arsene Wenger's men in their secondary competition for the rest of the season.
Rule 53 of UEFA's hand guide states: "No number may be used by more than one player on a team and no player may use more than one number in the course of a season."
Such regulations mean that Mkhitaryan will wear a vacant shirt number in Europe, while he is free to wear chosen shirt number seven in the Premier League and, potentially, the Carabao Cup final if Arsenal beat Chelsea in the semi-final second leg clash on Wednesday.