Manchester United's fans won't have a chance to see JJ Gabriel in Premier League action at Old Trafford this season, so a good proportion of the 2,516 who saw him feature in the 3-2 FA Youth Cup win over Sunderland made sure they got their selfies. As he only celebrated his 15th birthday in October, Gabriel currently falls foul of the Premier League regulation that players must be 15 by 31 August of the season in question to be allowed to play. In other words, they have to be in Year 11 at school. That is what makes Gabriel such a special talent. Despite being a Year 10 in school terms and, physically, much smaller than the vast majority of the players he is playing with and against, he still tends to stand out. The victory against Sunderland that earned United an Old Trafford semi-final with Crystal Palace, who they also meet in the Premier League Under-18 Cup final at Selhurst Park next month, wasn't his best performance. But he still produced a couple of magical moments.…