Steven Tyler Badly Injured After Slipping in Hotel Shower

Steven Tyler smashed his face during a "nasty fall" in a hotel shower ... knocking out several teeth ... this according to multiple reports out of Paraguay.

Tyler -- who was scheduled to perform in Paraguay with Aerosmith tonight -- was reportedly rushed to a nearby hospital.

A rep for the venue where the band was supposed to perform tells TMZ ... tonight's concert has been canceled.

No comment so far from Tyler's rep.

Story developing ...