He told BBC Sport: "I just let him play. I think they started the competition well, they won 3-0, he scored the penalty and got an assist. So I think he started OK.
He just plays and that's all he's done during his time playing.
"I think it's very unfair for anyone to expect him to go and do all kinds. He's just playing, he's a 15-year-old boy playing his football, enjoying it. Of course he gets different attention to a lot of his team-mates but I think he handles that really well.
"He has great coaches at Manchester United, so I take a stand off approach. I speak to him, but for me it's all about his mentality and his mindset, to make sure he keeps enjoying it - that's the main thing for me."