De La Hoya, who was billed as Chavez's heir apparent because of his combination of youth, size, power and speed, fulfilled his potential with a convincing, one-sided win.
In the first round he opened a cut above the Mexican's eye with two straight lefts. Chavez, in his 100th professional fight, brought experience, guile and his usual relentless attack. But De La Hoya took full advantage of superb hand speed and the age differential.
Chavez, who won his first world championship, the WBC super-featherweight title in 1984, never hurt De La Hoya, while the American steadily improved as the bout progressed and prevented Chavez from getting inside where he is most effective.
The end came after 2min 37sec of the fourth when the referee, Joe Cortez, halted the bout on the advice of the ring-side doctor, Flip Homansky, after a barrage of hooks, jabs and combination punches from De La Hoya left Chavez's face covered in blood.
De La Hoya, who said that Chavez was an idol of his, won all three rounds on the three judges' scorecards and landed 94 punches compared to Chavez's 35. The victory for De La Hoya, who won the International Boxing Federation lightweight championship last year, was his most convincing to date. It was Chavez's most crushing defeat.
"I knew if he got injured, he'd be in trouble," De La Hoya said. "When my left hook caught him and broke his nose - and I think I felt it break - I knew I had him."
De La Hoya said he next wants to fight the WBC welterweight champion Pernell Whitaker, of the United States, and then the IBF counterpart Felix Trinidad, of Puerto Rico.Reuse content