Did he quit?

[match]

Yes, he quit, much like how Tyson quit against Holyfield. Zab had a nice little flury at the end of round 8 and it didn't even phase Clottey, that right there was the moment he knew he couldn't beat this guy, much like Tyson had that flurry to open round 3 and Holyfield just stood there and kept coming forward like a monster movie. That type of thing psychologically scares mentally fragile fighters and they immediately look for a way out.