Jordie Barrett in doubt for Rugby World Cup opener

The All Blacks are sweating on the fitness of midfielder Jordie Barrett ahead of this weekend's Rugby World Cup opener against hosts France in Paris.

Barrett hasn't trained for the past two days as he nurses a knee injury, which has put him in doubt for the highly anticipated test.

The 26-year-old has been given "today and tomorrow" to prove his fitness.

Assistant coach Scott McLeod delivered the news at All Blacks training in Lyon today.

"He's just got a niggle. We are just taking precautions."

"It's a wait and see. It's still early in the week for us. So, we will just wait and see how he responds today and tomorrow to a little bit more treatment."

Barrett and Rieko Ioane have formed the main centre combination in recent All Blacks games.

The team will be named Thursday morning and if Barrett is unavailable he's likely to be replaced by either Anton Lienert-Brown or David Havili.

"Always. That is what we do [have contingency plans]," said McLeod

"Our whole squad prepares to play, right up until warm-up and the game day.

"He [Barrett] has been really important to our play. However, we trust our full squad and we are going to have to in this World Cup.

"He's a little bit frustrated with it, as would any athlete. Same as Tyrel Lomax (injured prop). They just have to go through what they have got to do and trust our medical staff, who are world class, and see how the treatment goes."