unknow song

[skipj]

hi,
some mounth ago i saw "crossroads" (the Walter Hill's film (1986)).
after about 13 minutes (from the start) R. Macchio plays a short acoustic blues piece.
does someone knows the title (or the author) of that beautiful song, or a similar song?
Ry Cooder was responsible for the soundtrack, but i din't find anything on his cd.
i've been searching that song for long time!

thanks