The former Wales internationals disagree over the Wales number 10 jersey for the match against New Zealand

Shane Williams has warned Steve Tandy against damaging Sam Costelow's confidence by dropping the fly-half for Wales' clash with New Zealand, after former centre Tom Shanklin called for Dan Edwards to be brought into the starting line-up.

Shanklin believes Edwards should be handed the No.10 jersey for Saturday's Nations Championship showdown with the All Blacks at the Principality Stadium, despite Costelow helping Wales secure a 28-21 victory over Japan.

The Scarlets fly-half started that match, with Ospreys youngster Edwards introduced from the replacements bench in the second half.

But Shanklin believes Edwards could offer Wales a greater attacking threat against New Zealand, identifying the fly-half position as the one change he would make to the starting XV.

"I'd go with Dan Edwards at 10," said Shanklin on Scrum V.

"There were a couple of opportunities in the Japan game I thought where Sam Costelow ended up kicking the ball away.

"I think [Edwards] will be better for Wales' attack against New Zealand because you are going to need more ball movement.

"I think Dan is a better option at that and getting the backline going. He is probably more of a threat ball in hand as well and offers a bit more in attack."

However, Williams strongly disagrees with the suggestion that Costelow should make way, believing Tandy must resist the temptation to change a winning team and risk undoing the confidence the fly-half has built up.

"If you said now that Sam has had his go, now we're going with Dan, he [Costelow] is going to lose all that confidence he's gained from the good things he did yesterday [against Japan]," Williams said.

"We can't then say come back now against Australia and dominate again because I don't care who you are, it affects your confidence.

"So I would not make any changes. They've got the job done with the bonus point win and I don't think anyone played poorly, although there is a lot to work on."

Former Wales scrum-half Richie Rees also believes there should be continuity in selection, with both pundits making the case for Costelow to retain his place.

"What I wouldn't do now is go chopping and changing over the next couple of weeks," said Rees.

"So I would keep Sam at 10."

Rees also believes Tandy needs to start giving Wales' other scrum-half options more opportunities, after Tomos Williams again played the full 80 minutes against Japan.

Reuben Morgan-Williams was an unused replacement, despite Wales having other options in the squad, including Che Hope.

"The difficulty we've got is there's huge trust in Tomos because he is one of the best players on the field," said Rees.

"We also have to start blooding someone else behind Tomos and giving them that opportunity. If not against Japan at home, then when?

"Reuben has been playing well over the last two years and we also have Che Hope in the squad."