Lee O'Connor was added to Manchester United's Champions League squad ahead of last night's defeat to Barcelona.
The 18-year-old fullback is yet to feature in a senior match day squad. He is currently listed as suspended by Uefa after he was sent off in an U19s Uefa Youth League game against Midtjylland last month.
The London Evening Standard says it is thought that the defender's inclusion was because of a potential suspension nightmare for boss Ole Gunnar Solskjaer ahead of the second leg in the Nou Camp next week.
The Norweigan had three first team full backs –Ashley Young, Luke Shaw and Antonio Valencia – all one yellow card away from suspension. Uefa do not allow teams to make changes to their squad in between legs of a tie.