U.S. champion Kibwe Johnson seized the lead with his first throw and never relinquished it to win the men's hammer at Thursday's opening day of the U.S. Olympic trials at Beaverton, Oregon.

"Coming in I wanted to have a season-best throw and I got that so I am definitely happy," Johnson told reporters.

Johnson, whose fifth throw sailed 74.97 meters, will be joined on the American team for London by third-place finisher A.G. Kruger, whose best was 73.93.

Runner-up Chris Cralle does not have the Olympic qualifying standard. He threw 74.36 on Thursday.

Amber Campbell, Amanda Bingson and U.S. record holder Jessica Cosby made the women's team.

Campbell edged out Bingson by two centimeters, throwing 71.80 in the fifth round.

"As soon as I let it go and hit it I knew it would be a good throw," said the 2008 Olympian.

Cosby's best was 70.77, well below her national record of 74.19 earlier this month.

The competition was held on a specially constructed hammer cage in the Portland suburb of Beaverton.

The remainder of the 11-day trials begin on Friday in Eugene, more than 100 miles south of Beaverton.

(Editing by Peter Rutherford)