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All Blacks star Sonny Bill Williams will be out to impress at the Sydney Sevens this weekend after New Zealand Sevens coach Gordon Tietjens afforded him a "big pass mark" following his debut at the Wellington tournament.

The code-hopping star still has plenty of work to do to secure his place at the 2016 Rio Olympic Games after he mixed the sublime with the ridiculous at Westpac Stadium.

Williams scored a try with his first touch in Sevens rugby and then again during New Zealand's quarter-final win; but some wayward passes, one of which almost cost New Zealand the Wellington Sevens crown, showed he is anything but a walk-up selection for Rio.

"Williams from my perspective was certainly a big pass mark for somebody who has never played sevens," Tietjens said.

"It's a challenging game, the conditioning factors of each athlete that plays this game and coming out of 15s; but he's a real professional and he gave me everything that I wanted.

"One tournament for Williams and one tournament victory, so it's a pretty good start for a Sevens career really. He's got a great goal and challenge, he wants to be an Olympian and you'll see an improvement with every tournament he goes to, which is what it's all about; giving him that real opportunity."

Williams' physicality, versatility and background in rugby league will serve to benefit the two-time Rugby World Cup winner as he learns his role as a sevens forward.

"He is quite versatile," Tietjens said. "You can put him in the backs, you can put him in the forwards.

"I guess the best way for him to learn sevens rugby is to play him in the forwards, then he can slowly get on top of the game and then there may be opportunities putting him in the backs.

"Where the game of sevens I think has really changed is the physicality and the breakdown, the size factor. I think a lot of teams now have a lot of big men, we've got a very big side, and of course what he [Williams] brings to the table is his physicality and his defence from being a league player.

"A lot of league is based on defence; he's a big tackler and is very, very good in contact. So anything you can add on top of that is a real bonus. But having his physicality, the way that he can defend and also what he can do in attack is also a huge positive for us."

Likely to be given up to eight tournaments to prove his mettle, Williams will have further opportunities to impress Tietjens. But he is competing with a host of New Zealand Sevens regulars for one of 14 Olympic spots.

"I've always said when you're looking to pick any team, the guys who have the head-start to go to Rio are the sevens specialists -- they understand and play and train the game the all the time," Tietjens said.

"So if a new player comes into our environment, a Super Rugby player, he's got to prove that he's a lot better than the players in the side, and if you can justify that then you select them; if you can't you don't select them. "

For Wallabies star Quade Cooper, it will be even harder to book a flight to Rio after he missed selection in the Australia squad for Sydney.

Flying halfway across the world just days before the tournament, Cooper couldn't prove himself to selectors and will now only have the chance to showcase his skills at London, Paris and possibly Las Vegas.

"For some players they can make that transition in a short space of time, but it's generally players that have played sevens before, they can make it," Tietjens said of Cooper's chances of making Australia's Olympic squad.

"But if players have never been involved in the sevens game then it's a real, real challenge. You've got to play lots and lots of sevens and train lots of sevens to be good at sevens, and that's really what it comes down to.

"Cooper has all the skillsets to be a fine sevens player, it's the conditioning factors that he'd have to get used to; training, eating, breathing, sleeping, training sevens, that's really what it comes down to.

"And also getting out there, there's a lot more accountability around defence so you're challenged a lot more; you can't cover yourself up out on the sevens field, so he'll be challenged there. But he's got all the attacking skills in the world; he's a great rugby player."