This is easily the video find of my entire time here. This is a video of highlights from Francesco's first derby when he was with A.S. Lodigiani as an 11 year old. I recall seeing him comment on this on Sky Italia or something a few years back as well.
I'm 99.9% sure he's #4. Or you could just watch for the kid tearing through everybody else. (They won 2-0....duh.)
No embedding, here's the link.
(Lodigiani being the youth team he played for before signing with Roma in '89 - the rest, as they say, is history.)
Totti scoring against Alessandro Nesta's Lazio as a boy, still with Lodigiani.