Crouch believes there's only two players who are better than the left winger.
He said: "Gareth is good but he's got some way to go before he gets to Lionel Messi's standard.
"He sets the bar high, although Messi and Cristiano Ronaldo are on their own at the moment. Bale is still only young and developing.
"In his wide position, he is right up there and what he did to Inter Milan over two games showed everyone what he's capable of.
"The biggest threat to us, of course, is Gareth and when he's on fire he is dangerous. But best in the world? Not yet.
"He will certainly be in our thoughts. We may have to double up on him.
"If we stop him, we will certainly cut in half the threat from Wales."