Sonny Bill Williams admits feeling like a schoolboy again as he finds his way with rugby's world No.1 All Blacks.

Yet to make his international debut in union, the former rugby league Test star says he's faced a steep learning curve and is swotting as hard as he can.

The sole new face in the tour squad currently preparing to start a grand slam tour against England at Twickenham on Saturday, Williams was grateful for the plentiful help he was getting, notably from imcumbent inside centre Ma'a Nonu.

"It's pretty intense," said Williams. "I've never experienced anything like this before.

"The biggest difference to when I played at the top level in league is here you notice how different the games are.

"League's a pretty simple game. In rugby there a whole lot of set piece, scrums, back moves and such to cover.

"It's been a big learning curve. I just try and be like a sponge. Hopefully, I get my shot soon.

"It's just like school. I go home, get that notepad out and jot things down. Last week was pretty tough, it was like a teething process. At the moment I'm feeling pretty confident with all the moves and what we're trying to achieve on the field."

Williams paid tribute to Nonu, who currently occupies his favoured inside centre berth in the All Blacks' Test side, for showing him the ropes.

"Ma'a's really taken me under his wing on the finer points of what we're trying to achieve as All Blacks.

"From the outside coming in I was probably a bit anxious to see what the boys were like. Everyone's been great, you ask a question you get 10 answers."

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