Jones Jr had too much hand speed for Ruiz More photos from the fight

The 34-year-old's unanimous points win means he becomes the first former middleweight champion since 1897 to capture the heavyweight title.

Despite conceding weight, height and reach to the Puerto Rican, Jones Jr produced a masterclass in technical boxing and picked off the 31-year-old Ruiz at will.

"My whole idea was to make history for the fans - this is what the fans wanted to see," said Jones after his victory.

"If I didn't go after quality fights I wouldn't be champion of the world right now."

What now for Jones Jr

After weathering a brief, early storm from Ruiz, Jones was never in trouble and was even able to indulge in some showboating.

A peach of a straight right rocked Ruiz towards the end of the fourth round and the champion went back to his corner with a bloodied nose.

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Once he had established a lead in the contest, Jones Jr was content for the most part to hit and run and the American just had too much skill and hand speed for Ruiz.

Jones has now won 48 of his 49 fights, with his only defeat coming via disqualification against Montell Griffin in 1997.

The Jones Jr v Ruiz bout was the feature fight on what was a top-class bill in Las Vegas.

Earlier action saw Jean-Marc Mormeck of France defend his WBA cruiserweight title with an eighth-round technical knockout of Ukrainian Alexander Gurov.

After a slow start, the Frenchman began to find his jab and forced Gurov into a standing eight count in the seventh round.

And shortly after, the referee stepped in to stop the fight after Mormeck waded in with a vicious combination.