Marcus Rashford looks set to take over the No.10 shirt at Manchester United after wearing the jersey against Bayern Munich.
The striker was named in the starting eleven and United fans quickly spotted Rashford was not wearing his usual No.19 shirt.
Zlatan Ibrahimovic was the last Red Devil to wear the No.10 shirt, having inherited it from long-term owner Wayne Rooney.
Marcus Rashford is considered as a United great in the making, and fans were delighted to see the youngster emerge with the iconic number on his back.
The Bayern game is certainly an indication Rashford will wear the shirt for the coming season, but United are yet to confirm their squad numbers to the Premier League.
United take on Leicester City in their league opener on Friday, with Rashford set to play some part in the game after returning late to pre-season.
Rashford and his World Cup team-mates were given extra time off this summer after a busy tournament in Russia.
England and Rashford reached the semi-final and then stayed on in Russia to play the third-place play-off against Belgium.
Mourinho was delighted when first-team quartet Romelu Lukaku, Rashford, Phil Jones and Victor Lindelof cut their holidays short to link up with the squad last week.
The United boss has expressed concern about the state of his squad after been made to do without most of his star men for pre-season. Centre-back Lindelof started the game against Bayern alongside Rashford, while Jones made the bench.