A back injury has Cronulla captain Paul Gallen in doubt for Saturday’s NRL qualifying final against the Raiders in Canberra.

Gallen struggled with the injury at the Sharks’ captain’s run on Friday at Southern Cross Group Stadium and didn’t board the team bus to Canberra.

The forward will continue his rehabilitation on his troublesome back in Sydney in a bid to be fit for the match.

It is anticipated Gallen will drive the 300km south on Saturday before the 5.30pm kickoff at GIO Stadium.

If he is ruled out of the match, Jayson Bukuya will likely shift into coach Flanagan’s starting side with Kurt Capewell coming onto the interchange bench.

Gallen’s omission would hit the Sharks hard . They go into the clash as underdogs having won just one of their past seven games, a 37-12 win over the lowly Sydney Roosters.

Canberra are on a 10-game winning streak.

“They are favourites to win and so they should be – they are in good form,” Flanagan said.