Tony Zale was dropped 3 times and counted out a round by Jimmy Clark in early 1938. Got 2 revenge kos over Clark in the same year, dropping him 13 times in 2 rounds in the 3rd match.
Joey Maxim getting starched in 1 by Curtis Sheppard. I was going to say John Ruiz being blitzed in 1 by David Tua until I read the title again seeing how it said ATG, so we'll leave that out.
YCIII's 1st round stoppage loss to McLarnin came after he became world champion, but before his victory over Mickey Walker, as well wins vs the bigger trio Billy Conn, Fred Apostoli and Gus Lesnevich, all of which combined saw him attain ATG status in my eyes.
Well Barkley and Jackson lost to Benn and McClellan in the 1st round before going on to win world titles again.
Roger Mayweather Ko'd in 1 round by Rocky Lockridge. He held multiple major and minor world titles and also trained Floyd.
John The Quiet Man Ruiz for the questionable stoppage he suffered against some opponent in a some questionable night of young heavyweight promotion. Most scholars discount this aberration.
Not sure if Amir Khan is an ATG but he lost in the first round fairly early in his career against Prescott before becoming champion later on. Not quite first round but Lennox and Wlad lost in the second round early in their careers too.
