NEW YORK -- Ricardo Lopez, small in stature but very big in talent, knocked out Zolani Petelo of South Africa in the eighth round, retaining the IBF light-flyweight championship Saturday night in Madison Square Garden.

The 35-year-old Lopez knocked down Petelo in the second round and then finished him at 1:32 of the eighth for his 50th victory against one draw. It was his 37th knockout.

The fight was part of a pay-per-view telecast featuring the undisputed middleweight championship between Bernard Hopkins and Felix Trinidad.

Lopez, a former WBC and WBA mini-flyweight champion, boosted his record in championship fights to 25-0-1 with 19 knockouts.

The champion from Mexico, who weighed 107, one pound under the limit, took charge from the outset against the willing Petelo, 107 1/2.

In the eighth round, Lopez staggered Petelo with a right to the jaw, then landed a left and right that sent Petelo backward and onto the seat of his trunks. He took the 10 count from referee Arthur Mercante Sr.

The fight was the 145th and last championship bout for Mercante.

In a 10-round super bantamweight fight, which was also televised, Ratanachai Vorapin of Thailand won the last two rounds on two of the three official cards and scored a majority decision over Danny Romero, a former IBF junior bantamweight champion from Albuquerque, N.M. Each fighter weighed 122 pounds.

In the first title bout on the card, Byron Mitchell got up from a 12th-round knockdown and retained the WBA super-middleweight championship on a split decision over Manuel Siaca, 167 1/2, of Puerto Rico. Mitchell, 168, of Ozark, Ala., scored a first-round knockdown.

The bout was fought before a nearly empty arena because it started at 6:23 p.m., only eight minutes after the doors were opened to ticket holders.

In a 12-round IBF welterweight championship elimination bout, Michele Piccirillo, 146 1/2 of Italy, boxed his way to a unanimous decision over Rafael Pineda, 146 1/2, a former IBF junior welterweight champ from Colombia.

Piccirillo, billed as the "Gentleman of the Ring", scored a knockdown in the fifth round and then was penalized a point for hitting Pineda while he was still on the canvas.

Nelson Dieppa, 108, of Puerto Rico retained the WBO junior flyweight championship with an easy decision over Fahlan Sakreerin, 107, of Thailand.