Green Machine fullback Charnze Nicoll-Klokstad went off with blood streaming from a nasty compound dislocated finger.

It came just before Raiders winger Semi Valemei showed brilliant reflexes to score a stunning try that was not only the 21-year-old's first in the NRL, but also the decisive one in the 18-12 victory at Canberra Stadium on Saturday night.

But it's not just forwards the Raiders need to look at signing, they're fast running out of backs now as well.

Nicoll-Klokstad's expected to miss at least a couple of weeks.

He'll have plenty of company in the rehabilitation room, joining fellow outside backs Bailey Simonsson (shoulder) and Michael Outfield (hamstring).

The positive was it led to Canberra-born Harley Smith-Shields making his NRL debut.

They've recently signed Corey Harawira-Naera and are on the verge of landing Ryan James as well, but their backs are starting to dwindle now.

Nicoll-Klokstad's injury allowed Jordan Rapana to show his versatility when he shifted to fullback - although he finished the game on the sidelines after a nasty collision with Valemei.

He was excellent under the high ball and produced a try-saving tackle on Reynolds as the Raiders held onto the lead.

But Rapana was fine after the game and should be right to travel to Townsville to play the North Queensland Cowboys next week.

Raiders coach Ricky Stuart said they'd just bring in another player and look for them to do their role.

"Apparently it's a compound fracture in the finger. We've got another one out now," he said.

"We'll just keep punching and find somebody else to come in and roll their sleeves up and take that role."

Stuart said Smith-Shields looked at home on the NRL stage, even though both he and Valemei had been brought in earlier than either probably expected.

He said they were being conservative with Curtis Scott's arm infection, but John Bateman (shoulder) was close to a return.

They could also welcome second-rower Corey Harawira-Naera for his Raiders debut if he passes the Project Apollo protocols.

"This is all coming a little bit earlier than they expected, these debutants - Semi, Kai [O'Donnell], Harley - but for the future of the club it's wonderful they're getting some first-grad experience and they're being taught how to win in tough games," Stuart said.

The Raiders shot out to an early lead off the back of two Jack Wighton kicks - the first Rapana batting back for Nick Cotric to score and the second a brilliant pick up by Jarrod Croker.

But tries to Dane Gagai and Adam Reynolds gave Souths a 12-10 half-time lead.

The rain came with the second half and the game became an enthralling armwrestle until Valemei reacted like a slips fielder in cricket to score the winner.

A Whitehead kick ricocheted into the Fijian's arms and he barged over in the corner.

With the Rabbitohs pressing in the dying seconds, Canberra prop Dunamis Lui produced a crucial one-on-one strip.

Stuart praised Lui, who has been especially good the past two weeks - almost taking over from injured co-captain Josh Hodgson as Canberra's one-on-one-strip king.

"We're down on a number of troops ... we only had 20 available and a heap of rookies," Stuart said.

"I've got two rookies playing at the moment and that's the character of the club - being able to hang in there tonight the way we did.

"But again, so did Souths. They lost their fullback early, we lost ours later in the game ... it's just a matter of jumping into a position I gave them and having to find a role."

AT A GLANCE

CANBERRA RAIDERS 18 (Nick Cotric, Jarrod Croker, Semi Valemei tries; Croker 3 goals) bt SOUTH SYDNEY RABBITOHS 12 (Dane Gagai, Adam Reynolds tries; Reynolds 2 goals) at Canberra Stadium. Referee: Ashley Klein.