Bernard Jackman believes that Joe Schmidt's World Cup preparations would be best served by giving outhalf Joey Carbery the No 10 jersey against Italy on Sunday.

Carbery has started five games for Ireland since making a memorable debut as a replacement in the historic win over New Zealand in 2016 but never in the Six Nations.

The Munster outhalf did play over 57 minutes when Jonathan Sexton was forced off injured against Scotland and recovered from being at fault for an intercept try to lead Ireland to victory.

However, with the World Player of the Year having played only 103 minutes of rugby in 2019, Ireland head coach Schmidt might feel he can't afford to experiment.

"It's unfortunate that Sexton has had such little game time," former Ireland international Jackman told 2fm's Game On.

"He had an injury in January, which does make the argument that you let him play.

"I think Johnny is number one but Carbery did well against Scotland and for him to start a Test match... it's not just starting, running the show all week is a huge thing.

"At some stage, we're going to need Joey Carbery to be able to come in on a Monday morning and be like the quarterback, to actually run the team that week.

"More than likely when Johnny picks up an injury, and that could be a key match in the World Cup.

"So I think this is a great opportunity to give him game time at the start and have Johnny on the bench to give him 30 minutes if he needs to.

"For France we have to play our best team."

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Jackman expects "maybe four or five changes" in the team, which will be named on Friday.

"I'd like to see a change at hooker, give Cronin a start, Kilcoyne a start," he said.

"The fact that Iain Henderson got off that citing, it's a great opportunity to get him into the game.

"Carbery to play at 10 just to look after Sexton a little bit and Robbie Henshaw maybe to come back into the centre."

Follow Italy v Ireland (Sunday, 3pm) via our liveblog on RTÉ.ie/sport and the News Now app, or listen to live national radio commentary on 2fm.