"The grim injury update on Williams compounded a disastrous opening day for Gordon Tietjens' side," said Keane of the setbacks the Kiwis men suffered.
"Japan would not buckle and they secured a famous victory through Kameli Soejima's late touchdown that Katsuyuki Sakai converted.
"New Zealand can still qualify for the quarter-finals from Pool C with two matches remaining but the defeat will be a major blow to their confidence as they look to become the first men's rugby sevens Olympic champions."
Australia's Daily Telegraph was equally shocked and with Williams having such a high profile across the Tasman, the news outlet also led its Rio coverage with SBW.
Under a headline of "SBW's Olympic dreams in tatters", Iain Payten wrote: "Japan stunned New Zealand 14-12 in their opening match of the Olympic rugby sevens in an echo of Japan's famous victory over South Africa in the 15-a-side World Cup in Brighton, the biggest shock the sport has ever seen."
The Sydney Morning Herald also led its website with Williams.
"It is a devastating blow for Williams, who had concentrated solely on making the transition from the All Blacks to sevens rugby to compete in the Olympics," wrote the Herald's Andrew Webster.