Sonny Bill Williams: We're just a work in progress

Sonny Bill Williams made an instant impact as New Zealand opened their World Cup defence with victory against Argentina, but says there is plenty of work to do.

Williams, who has flitted between codes and had a spell in the NRL with Sydney Roosters after helping the All Blacks win the 2011 World Cup on home soil, provided plenty of attacking impetus when he came on at Wembley in the 26-16 win.