The ex-United player has been at the Emirates for more than two weeks now. His 'swap' deal for Alexis Sanchez also saw him take on the Chilean's shirt number: '7.'
Now, Henrikh Mkhitaryan has appeared with '77' printed across his back and there's a very simple reason why...
UEFA doesn't allow players to inherit shirt numbers in the same edition of it's Europa League competition and, since Alexis had already played under the number '7', it was thus out-of-bounds for the Armenian.
Mkhitaryan will continue to wear numer '7' in the league. His double '7' will be reserved exclusively for the European competition.