After their 2-2 draw with Tottenham, Megson said: "If Kevin played for England and was utilised in the right manner he would be a huge threat.
"In our European games the opposition moaned and groaned all night because they could not handle him. The lad cannot do any more. Every manager bar none tells me after a game they are glad they do not have to play him every week."
At only 23, Cahill looks sure to get his chance particularly if he keeps making progress as he has done in recent weeks.
Megson said: "Crouch is a real handful, as much as Kevin Davies in the air, but he wasn't such a handful today because of the quality of Gary Cahill.
"If there is a better centre-half in the country I have not seen him."