Dylan Armstrong of Kamloops, B.C., competes in the men's shot put event Friday. (Ryan Remiorz/Canadian Press)

Dylan Armstrong of Kamloops, B.C. was on the cusp of achieving Canada's first medal at the Beijing Olympcs, but settled for fourth place in shot put.

Armstrong set a Canadian record with a distance of 21.04 metres on his fifth throw, and was in bronze-medal position with only two men left who could bump him lower.

Christian Cantwell of the United States did precisely that, going for 21.09 metres. The American leapfrogged Belarus's Andrei Mikhnevich, who had an existing throw of 21.05 metres.

Armstrong had his sixth and final throw to get back into podium position, but fouled for the third time.

"I worked my butt off all year and to come out here with the best in the world and place fourth, I think I did my country proud and did Kamloops very proud," said Armstrong.

Tomasz Majewski of Poland easily won the gold medal with a distance of 21.52 metres. He was the only man to go over 21 metres twice.

Cantwell took silver and Mikhnevich the bronze.

Armstrong said he wasn't watching when Cantwell made his critical throw.

"Chris is a great thrower. He's been No. 1 in the world for a number of years," said Armstrong. "The Americans are strong and that's competition."

Sets Canadian record

The 27-year-old Armstrong set a Canadian record with his distance of 21.04, and upstaged several competitors ranked ahead of him heading into Beijing.

Those men included Americans Reese Hoffa and Adam Nelson. Hoffa beat Cantwell at the U.S. Olympic trials, while Nelson won silver in the event at both the Athens and Sydney Games.

Hoffa finished seventh and Nelson fouled in each of his first three attempts.

Armstrong converted to shot put from the hammer-throw competition less than four years ago.

"I put in the time and the effort, and have just been disciplined, and I think that's what I did today and it just came out," said Armstrong. "You have to train hard and nothing comes easy."

Armstrong told CBC Sports he would be gunning for a medal at the 2012 London Olympics.