By Neil Maidment

LONDON (Reuters) - Moments after winning a second men's Olympic shot put title on Friday Poland's Tomasz Majewski was already contemplating a tilt at a third in Rio in 2016.

"Why not? If I am healthy, then why not. Three is a good number," the 30-year-old said smiling as he towered over a crowd of reporters.

Victory for Majewski, who took gold in Beijing four years ago, made him the first man to win the event twice since Parry O'Brien of the United States in 1952 and 1956 and the first non-American.

The pony-tailed Pole took the lead with his third attempt inside a lively Olympic stadium, edging one centimeter ahead of German world champion David Storl with a throw of 21.87 meters, which he confidently greeted by wagging a finger in the air.

With U.S. medal contenders Christian Cantwell and Ryan Whiting never really threatening and his closest rival on the night Storl failing to register a distance in his last three throws, gold was to be Majewski's. But not before one final flourish.

With the pressure lifted he stepped up to deliver a season's best throw of 21.89 to put three centimeters between him and Storl and add the gloss to a classy performance.

Majewski's previous season's best had been 21.72.

"It was a great feeling to defend the title," said Majewski, who after his win hugged his rivals warmly before running across track to drape himself in a Polish flag. "56 years ago Perry O'Brien did that, he was a legend. I'm very proud."

Reese Hoffa, the 34-year-old 2007 world champion, took bronze for the U.S. to keep a strong American presence in an event in which the U.S. has claimed medals in all but two of the Olympic Games that they have attended.

"The most important thing throughout this competition was to continue the tradition of the U.S. getting medals at the Olympic Games, so I am very happy," Hoffa said.

(Editing by Ed Osmond)