What kind of leaf is this?

This maple sprout a href="http://i56.tinypic.com/3353wa1.jpg" rel="nofollow"http://i56.tinypic.com/3353wa1.jpg/a is a few months old. I planted a few old-looking maple seeds this past winter, and this pretty little thing shot up in the spring. I asked this question before, and the only answer I got was that it was a silver maple (acer saccharinum). Looks nothing like a silver maple to me though. I think it's red maple (acer rubrum), but I'd like someone with experience to identify it. The two lowest leaves have reddish petioles, if that helps any. I'd also like to know the characteristics about the leaf that helped you ID it.