Alias: Baby Bull
Birthplace: Houston, Texas, USA
Hometown: Houston, Texas, USA
Height: 5′ 6″ / 168cm
Reach: 67″ / 170cm
Boxing Record: click
Díaz made his professional boxing debut at age 16 on June 23, 2000 with a first-round TKO victory over Rafael Ortiz.<ref name="boxrec">BoxRec.com editors. "Juan Diaz." BoxRec.com. He won all of his first five fights by KO or TKO.
On July 17, 2004, Díaz defeated Mongolian Lakva Sim for the WBA lightweight title by unanimous decision.<ref name="boxrec"/> Since then, Díaz has defended the title five times.<ref name="boxrec"/> His most notable defense was on April 8, 2006 against undefeated José Miguel Cotto (brother of Miguel Cotto). Díaz defeated Cotto by unanimous decision.<ref name="boxrec"/>. On November 14, 2006, Diaz successfully defended his title for the fifth time against Fernando Angulo of Ecuador.
On April 28, 2007 he successfuly defended his title against Acelino Freitas by TKO after Freitas forfeited the fight before beginning the 9th round, unifying the WBO lightweight championship with the WBA lightweight title. The fight took place in Mashantucket, USA.
Diaz was 105-5 as an amateur. He thought he had qualified for the 2000 Mexican Olympic team but was informed he was too young to compete in Sydney. He didn't want to wait four more years and turned pro.
| WBA Lightweight Champion
17 July 2004 – present
| WBO Lightweight Champion
28 April 2007 – present