Former rugby league halfback Greg Alexander has called upon the New Zealand Warriors to switch Roger Tuivasa-Sheck from the centres to the fullback spot for Round 4.

Alexander's call comes as Taine Tuaupiki will be unavailable this week due to a concussion he sustained against the Canberra Raiders, which will see Tuivasa-Sheck return to the number one jersey.

However, Alexander would double down on his statement, believing Andrew Webster should permanently move Tuivasa-Sheck to the fullback role and push Charnze Nicoll-Klokstad to the centres.

"He is your number one fullback. Charnze (Nicoll-Klokstad) still has to come back (from injury), I'd be playing Charnze in the centres and Roger at fullback. Roger's ready to play fullback," Alexander said on SENZ Mornings.

"The Warriors' performances haven't been bad. It took a miracle to beat the Warriors in Melbourne, the Storm came up with a couple of tries that just shouldn't have happened," he added.

"I guess the only critical part when you're looking at the Warriors' first two performances is can they score when they really need to?

"That was highlighted in Round 1 when they had a fair bit of ball against the Sharks at home, and couldn't get it done.

"To win 18-10, that's a really good win against a Raiders side that's traveling well. The Warriors were no way like other teams that were 0-2 coming into round three, their 0-2 was looking a lot better.

"So, I can understand the air of no panic over there in New Zealand even though it wasn't the start they were looking for."

A former Dally M Medal winner with the Warriors before making the code-switch to rugby union, Tuivasa-Sheck is focused on playing in the centres after returning to the NRL.

This goes with recent reports from members of the club's coaching staff that Tuivasa-Sheck is only willing to play in the number one jersey again if the situation calls for it due to injuries or suspensions to his teammates.