NRL: Canberra Raider Corey Harawira-Naera expected to miss at least a month as testing continues

The medical thinking around what caused him to collapse with 14 minutes remaining in the 33-26 win over South Sydney on Saturday was shifting towards being concussion related.

But at this stage there's no concrete answer, although it could be the accumulation of Harawira-Naera's previous two hit-ups and a tackle he made before that.

He struggled following both of his two runs and looked towards the bench just before he suffered the seizure.

Another possibility being examined was the virus he had in the lead-up to the game, which might also have played a role.

Once they have a more definitive answer, the Raiders medical staff will then formulate a return-to-play program - but at this stage it was expected to be at least 4-6 weeks.

Meanwhile, Sebastian Kris will be given until the last minute to prove his fitness to face the Wests Tigers after Canberra Raiders coach Ricky Stuart named him in the No.1 jersey on Tuesday.

Kris was unable to finish the win over South Sydney after he hyperextended his knee in the first half, with Jordan Rapana replacing him at fullback in the 25th minute.

Rapana's his likely replacement, although Stuart has named Xavier Savage on an extended bench for the game at Campbelltown on Friday night.

Either Savage or Harley Smith-Shields would come into the side if Kris can't play.

Co-captain Jarrod Croker's resting sees Albert Hopoate shift to the centres, with Nick Cotric named on the wing.

Raiders lock Joe Tapine will captain in Croker's absence, as the latter rests up for his 300^th NRL game - against the New Zealand Warriors at Canberra Stadium the following Friday.

NSW Blues second-rower Hudson Young has been named, although that will depend on how he pulls up following the State of Origin opener at Adelaide Oval on Wednesday.

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Corey Harawira-Naera's seizure meant Corey Horsburgh remained in the second row, with Tapine the likely cover if Young can't play.

Stuart has also named half Matt Frawley in the 17.

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