No pressure to pick SBW for Sevens

New Zealand Sevens boss Gordon Tietjens has said that he will only pick Sonny Bill Williams when he's ready.

Williams has switched to the new format of the game in time to try and make the cut for this year's Olympic Games in Rio.

The double Rugby World Cup winner has been training to get up to speed when it comes to his fitness and Sevens education, but he has been included the the provisional squad for next month's Sevens World Series leg in Wellington.

Tietjens however won't be pushed into picking Williams early if he's not ready.

"There’s no pressure to pick Sonny,” Tietjens told AAP.

“I’ll pick Sonny if he’s ready. He hasn’t played the game before. He’s got to be really ready and go in with a lot of confidence.”

Williams isn't the only player to switch from the 15-man game to Sevens and Tietjens admits some "rust" is expected at first.

“The guys that have came from 15s – to be fair, they have to make that transition,” Tietjens added.

“They are going to be a little rusty, which is probably normal. If things go along really well, they will be part of Wellington.”