At the weigh-ins Aug. 1 at the Cosmopolitan Las Vegas, KO artist Diego Chaves tells Molly Sullivan about his Visa struggles entering the U.S.A. & testing Brandon Rios's notoriously strong chin.

Rios-Chaves/Vargas-Novikov happens at 9:45p ET/PT Aug. 2 on HBO from the Cosmopolitan Las Vegas.

For fight updates go to WWW.TOPRANK.COM, Facebook at FACEBOOK.COM/TRBOXING and Twitter at TWITTER.COM/TRBOXING and twitter.com/trboxeo.