Chris Swift is a former pro with Stoke City.
He told the Daily Mail: "I honestly wasn't surprised.
"They should have had him in a few months ago. They needed goals and he scores them. He would have been in with a shout of the World Cup - if he'd been playing for Manchester United and scoring goals then there would have been a big chance."
Swift added: "I played for Stoke up to reserve-team level and I've seen a lot of very good players come through - but James is the best.
"You fear, by the time they're 18, things might level out. But he has handled everything physically and that has allowed his ability to show. He did not look out of place on Wednesday.
"He can go as far as he wants. It's up to him, he's that good."