[5] After reaching 55 wins in a row, including a five-round knockout of Truppi in a rematch, he met world jr. middleweight champion Sandro Mazzinghi in Milan, on 18 June 1965.

[7] A rematch with Mazzinghi took place on 17 December 1965, and Benvenuti retained the world junior middleweight crown after winning a fifteen-round decision.

After three non-title wins, including a twelve-round decision over Don Fullmer and a fourteen-round knockout in Germany of Jupp Elze (Benvenuti's first professional fight abroad), he travelled to South Korea, where he lost his world junior middleweight title against Ki-Soo Kim, who won by decision in fifteen rounds on 25 June 1966, breaking Benvenuti's record of 65 consecutive wins.

[5] Benvenuti beat Emile Griffith by decision in fifteen rounds at New York City's Madison Square Garden on 17 April 1967, in what was the beginning of their trilogy of fights, to win the world middleweight title.

Benvenuti broke his right hand while landing a head punch in the first round,[9] but chose to continue fighting "like a cripple" rather than quit.

[10] The most curious defence of Benvenuti's active reign, took place on 4 October 1969, when he retained the world middleweight title with a seven-round disqualification win over American Fraser Scott at the Stadio S. Paolo in Naples.

Scott, a young fighter unschooled in the European insistence on what his trainer referred to as "that...Olympic stand-up style", knowing only the battle plan he went in with and speaking no Italian, did not understand the warnings at first, then was unable to alter his approach; to the American, he was merely "ducking" Benvenuti's shots.

The bout was foul-filled even without this added controversy; Scott would later accuse Benvenuti of having tried to thumb him, and during the sixth round, the fighters' legs became entangled as they wrestled, causing both to crash to the canvas.

Round seven saw the stoppage, the referee asserting "attempted butting", Fraser Scott and corner forever insisting he had "ducked".

[12] On 13 March 1970, in a non-title bout, Benvenuti was knocked out in the eighth round by unknown American Tom Bethea in Australia.