Rabbitohs back Koroisau in grand final

Apisai Koroisau come on down. 

Veteran Souths hooker Issac Luke failing to get off a dangerous throw charge on Roosters back-rower Sonny Bill Williams at the judiciary on Tuesday night, meaning the Rabbitohs rake will miss the grand final against the Bulldogs and New Zealand's opening clash against Australia at the Four Nations later in the year.

With Luke out, Koroisau is now in line to make his 14th NRL appearance in what will be the biggest game of his young career and his final game for the club before he links up with the Panthers in 2015.

Luke took to Instagram on Tuesday night to express his disappointment but was still proud to be a part of the Rabbitohs season thus far.

"Time to rip up little brother @apikoroisau," Luke said. "I got your back g."

Replacing Luke is not an unfamiliar task to Koroisau, who held the No. 9 jumper when Luke was sidelined for two months with a shoulder injury earlier this season. 

It is that period that gives five-eighth Luke Keary confidence, backing the club's depth in the key position.

"Api has played some good footy this year and we have Cameron McInnes there as well who has played half a dozen first grade games this year too, so I thought they both did a fantastic job for us over those... weeks when Issac was injured," Keary said.

"We obviously have the depth there to cover for Issac and will be able to do the job on the day."

Grand final experience is hard to come by in the Rabbitohs team, with only Greg Inglis (four) and Lote Tuqiri (one) previously playing in season deciders, and Koroisau will be in the same boat as Keary and 13 other teammates when they run out onto ANZ Stadium on Sunday for their senior grand final debuts. Even star Englishman Sam Burgess didn't play in a decider in the UK Super League in his four year with Bradford before joining the Rabbitohs.

Their opponents will have an advantage in that category, with 10 members of the 2012 losing grand final side named (although that will likely drop to nine on the day with skipper Michael Ennis almost certain to withdraw), while their English import James Graham played six straight deciders for St Helens (albeit with just one victory) before joining Canterbury.

"I don't think you have to lean on or seek advice from anyone," Keary said when asked about the team's lack of experience. "We have a lot of young kids in this team so all we have to do is trust in ourselves and trust what we have done the entire year to get to this point."

Keary, a five-eighth who stands at 178cm with an 84kg frame, can expect plenty of traffic to come his way in the shape of Bulldogs edge runners like Tony Williams and Josh Jackson, but it won't stop him from putting his best foot forward. 

"Defensively I try to play with a bit of a chip on my shoulder. I don't want any big fella to think I'm an easy beat or they can run straight over me," Keary said.

"I pride myself on my defence and I think it is a massive part of every halves game having to be able to stand there, win your tackles and be strong defensively otherwise you're going to be targeted and it is going to affect the way you play footy."