Valerie Adams has remained on course to claim a record third consecutive Olympic gold medal after safely progressing past the qualifying round of the shot put.

The double Olympic champion, vying to become the first woman to win three shot put gold medals, wasted little time in bettering the 18.40m qualifying mark at a wet Rio Olympic Arena.

The 31-year-old sent the shot out to 19.74m on her first throw to book her place in the 12-thrower final.

No New Zealand athlete has ever claimed three consecutive Olympic gold medals.

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She is one of four athletes in the field to throw over 20m this year with a personal best of 20.19m last month. The others are China's Lijiao Gong (20.43m in May), defending world champion Christina Schwanitz of Germany (20.17m last month) and American Michelle Carter (20.21m in March to become world indoor champion).

"It is an even playing field and probably one of the tightest for Olympic year," Adams told the Herald last month.

"The level is not as high as previous Games, which is exciting, because I'm breathing down their necks. That's good for my confidence."

- with AAP