The 20-year old attacker was added to Roy Hodgson's Three Lions squad for the clash with Sweden on Wednesday after Manchester United's Wayne Rooney was ruled out with injury and Holloway was full of praise for the youngster.
"He's an untouched, pure talent and everyone knows the more serious you get the harder it is to want take people on," he told Sky Sports News.
"But he's so unique, I've never worked with anyone like him, he just wants to get the ball and beat people, however many there are, he can do it. Before I got to Palace I thought 'yeah, but is he any better than anyone else?' Now I've seen him, good gracious me, it's quite unbelievable what he can do.
"Hopefully, if he does play on Wednesday, people will see that and I believe he can do it at the very top level."