Moyes originally believed Rodwell would become more of a defensive midfielder than someone who chips in with goals aplenty.
But he is now starting to think the 19-year-old can become a real goal threat and that means going up against Cahill for a place in Everton's starting XI.
Moyes said: "Jack's come on a ton and bits of his game have sharpened up.
"We've also realised he's not ready to be an out-and-out defensive midfielder.
"He's probably more of a threat at the top end of the pitch where he could threaten the likes of Tim because he can run, come from deep and score.
"He's got a smell for a goal a wee bit and he's doing well going forward."