Valerie Adams hasn't been legitimately beaten in competition for more than three years and that's not likely to change this weekend at the Diamond League meeting in Oregon.

The 28-year-old two-time Olympic gold medallist is the headline act in the seven-strong field in the women's shot put at Eugene. The competition is the first in Adams' northern season and she heads to the US after a couple of niggling injuries to her elbow and knee.

"We are always careful not to expect too much in the first competition," manager Nick Cowan said. "But she's in very, very good shape after a good summer.

"From her and JP's [coach Jean-Pierre Egger] point of view, it's a measure of how things are going rather than a mark of where things are at. There's enough competition there for Val to have to step up."

Adams is the only one in the field to have thrown more than 20m this year, hurling the shot out to 20.37m to win her 12th national title. China's Lijao Gong is the next best with a throw of 19.97m and only Michelle Carter (US) and Russia's Irina Tarasova have surpassed 19m.

Adams is preparing for a tilt at a fourth world title in Moscow in August - hoping to become the first female thrower to win four world titles - and will also compete at Diamond League meetings in Lucerne, Paris, London, Stockholm and Zurich.

- APNZ