Sonny Bill Williams out of Olympics sevens

Sonny Bill Williams is out of the Olympics after being injured in the rugby sevens opening loss to Japan.

RNZ reports New Zealand suffered one of the biggest upsets in sevens history when they were beaten 14-12 by Japan.

In a double blow for the team Sonny Bill Williams has been ruled out of the tournament with a partial Achilles rupture. He has been replaced by Sione Molia.

Joe Webber also left the field with a suspected dislocated shoulder.

The New Zealanders struggled to get possession in the first half of the pool match against Japan - with the score 7-7 at half time - and Japan defended well after the break.

Scott Curry and Akira Ioane scored tries for New Zealand.