Controversial former All Black Sonny Bill Williams' rugby and boxing careers looks to have taken a blow after he was seriously injured playing for Japanese club Panasonic Wild Knights today.

Williams is expected to miss the rest of the Japanese season after being taken to hospital with a shoulder injury 10 minutes into the game against the Mitsubishi Dynaboars.

He had scored an early try and then took a high shot at former Western Force centre Gene Fairbanks who had broken the defence.

He caught Fairbanks but went over the top, landing on his right shoulder, and was taken straight to hospital with his arm in a sling.

The dual rugby international was expected to return to rugby league and join NRL side Sydney Roosters next year but the injury will have thrown a cloud on that move.

Williams reportedly was paid $1.2 million for his short stint with the Panasonic Wild Knights and could expect to receive more than $800,000 when he rejoins the NRL that he quit in 2008.

The New Zealand heavyweight title holder was due to South African veteran Francois Botha, 44, dubbed the "White Buffalo" in Brisbane next month.

He played for the Canterbury Crusaders in the 2011 Super Rugby tournament but moved to the Waikato Chiefs. He was in the All Blacks side that won the Rugby World Cup last year but he made most of his appearances off the reserves bench.
Williams' flambouyant manager Khoder Nasser was watching the game.