Steve Walters, the former Canberra hooker, turned to his coach Tim Sheens one day at training and said: ''I've got Ricky Stuart calling from one side, and Laurie Daley calling from the other - who do I go to?'' Sheens didn't waste much time replying: ''Gary Belcher.''

That was then. This is now. While a few decades ago, when Walters asked his coach that question, full-backs like Belcher were important, today they are even more so. And on Friday night at ANZ Stadium, South Sydney's Greg Inglis and Melbourne Storm's Billy Slater will show why.

''Both guys are going to have a fair influence on the outcome of the game,'' said Sheens, the Australian coach who has the luxury of having both in his World Cup squad.

Trying to argue why one is better than the other is like trying to state why a Bentley is better than a Porsche. They are brilliant for different reasons.

Inglis has the power to run over Sonny Bill Williams; Slater has the speed to go around him.

Inglis puts the Rabbitohs on the front foot from the start of a set of tackles; Slater gives the Storm perhaps the most dangerous option in the game in the attacking zone on the last.

If you look at the stats, Inglis has outperformed Slater over the course of this season. In the contribution value ratings (CVRs), NRL Stats has the Rabbitohs player ahead of his former teammate. But only just.

In his 18 matches so far this year, Inglis averages 471.67 in the CVG (contribution rating per game). That puts him ahead of Slater, who has averaged 462.92.

Would you trade Slater for Inglis? Or vice versa? The reality is that Inglis works for Souths, and Slater works for Melbourne. Both work for Australia in different ways. Which is why, when Sheens takes the pair over to the UK with the Australian squad, Slater will play full-back and Inglis centre, but will be a handy back-up No.1.

''When you've got a good full-back, you play with 14 men; if you don't, you play with 12,'' Sheens said. ''Both Greg and Billy bring special skill sets. Billy's got that elusiveness, GI's got that power. Based on what I've seen, there'd be half a dozen games this year that both teams wouldn't have won without them.''

Both players had injury clouds over them at times this season. Slater started slowly as a result of a knee injury sustained during last year's state of origin series. Inglis injured his knee in this year's origin III. His fitness is improving, although the heavy strapping suggests otherwise. Slater is looking ominous again.

''I think the last few weeks we've seen the best of Bill and that's probably the best we've seen of him over the last 18 months - ever since he injured his knee,'' Melbourne skipper Cameron Smith said. ''He looks like he's running more freely.''

Inglis has never been in a side that has beaten Slater - Souths have not beaten Melbourne since Inglis joined - their last victory over the Storm coming in 2010. Yet if he is more dominant than his Test and origin teammate, he should finally get one.

■ Melbourne Storm received a boost when injured five-eighth Brett Finch trained with teammates but Gareth Widdop remains favourite to fill the five-eighth role against South Sydney.

Finch suffered an AC shoulder joint injury last Saturday and was rated at long odds to play in the qualifying final. But he took to AAMI Park on Thursday for a training session following a week of intense treatment.

''Finchy and Gaz both trained in that five-eighth position, so we're not sure [who will play],'' second-rower Ryan Hoffman said.

South Sydney has its own injury concern, with interchange forward Jason Clark suffering a knee injury at training on Tuesday.

With Steve Mascord

NRL QUALIFYING FINAL - South Sydney Rabbitohs v Melbourne Storm

ANZ Stadium, 7.45pm

Greg Inglis, Nathan Merritt, Bryson Goodwin, Dylan Walker, Dylan Farrell, John Sutton, Adam Reynolds, Thomas Burgess, Issac Luke, Roy Asotasi, Chris McQueen, Ben Te’o, Sam Burgess.
Luke Keary, Jeff Lima, Jason Clark, George Burgess

Billy Slater, Sisa Waqa, Will Chambers, Maurice Blair, Justin O’Neill, Brett Finch, Cooper Cronk, Jesse Bromwich, Cameron Smith, Bryan Norrie, Kevin Proctor, Ryan Hoff man, Ryan Hinchcliffe.
Interchange (from): Jason Ryles, Tohu Harris, Jordan McLean, Kenneath Bromwich, Gareth Widdop.

Referees: Shayne Hayne, Jared Maxwell