LAS VEGAS -- Unbeaten Tim Austin, defending his IBF bantamweight title for the ninth time, stopped Adan Vargas in the 10th round of their scheduled 12-round championship fight Saturday night.

Austin dominated the bout most of the way against the challenger from Hidalgo, Mexico, but there were no knockdowns. Austin, from Cincinnati, ended it with a flurry of punches that left Vargas defenseless.

Referee Tony Weeks stopped it at 1:03 of the round.

Austin, who weighed 118, kept Vargas off-balance with his jabs, and began landing telling left hooks in the later rounds. Vargas never backed off, but the punches he landed did not seem to affect the champion.

Austin is now 25-0-1, with 22 knockouts. Vargas, ranked the IBF's No. 5 challenger, is 37-4-1, with 23 knockouts.

Austin won the crown with an eighth-round knockout of Mbulelo Botile five years ago.

In another bout on the undercard of the John Ruiz-Kirk Johnson WBA title fight at Mandalay Bay Events Center, WBA super middleweight champion Byron Mitchell, knocked down twice in the opening round, came back to stop Julio Cesar Green in the fourth round when the ringside doctor decided Green should not continue.

Dr. Margaret Goodman determined that the bout should be halted because Green had a deep gash below his left eyebrow, his pupil in that eye wasn't reacting properly, and he had deep cuts inside his mouth.

The fight was stopped at 1:55 of the round.

Mitchell, from Ozark, Ala., improved his record to 25-1-1, with 18 knockouts. Green, the former two-time WBA champion from the Dominican Republic, is 25-5-1.

Mitchell weighed 167½, and Green 168.

Pete Frissina defended his NABO bantamweight title with a unanimous 12-round decision over Jesus Perez. Frissina, from Tampa, Fla., weighed 117 as he improved his record to 26-3-1, with 15 knockouts. Perez, 118 pounds, from Cordoba, Columbia, is 22-2-2.

In scheduled 10-round bouts, Tommy Martin, 240, of Davie, Fla., stopped Andy Sample, 210, from Topeka, Kans., in 2:59 of the first round of their heavyweight match; heavyweight Lamon Brewster, 224, of Los Angeles, stopped Willie Chapman, 221, Salt Lake City, at 1:32 of the sixth; and welterweight Jose Rivera, 147, of Philadelphia, stopped Elias Cruz, 149, of Miami, at 2:59 of the second.