Wallabies coach Michael Cheika wants to see more from Lopeti Timani and the Melbourne Rebels forward has the perfect chance to show his Test credentials against incumbent Australia lock and Brumbies star Sam Carter on Saturday night.

Australian derbies were always going to provide key indicators for Cheika, who is balancing two jobs, this season as he looks to find 32 players for an assault on the Rugby World Cup. And after watching the Rebels forwards go toe-to-toe with his Waratahs pack last weekend, the former Randwick enforcer picked up his Wallabies brief and added to the file labelled 'Timani'.

"I had the opportunity to coach Lopeti and it's very obvious that he has a massive amount of physicality in his game," Cheika said following the Waratahs' 38-28 win. "The mastery for him will be about delivering it consistently so every week you know that he's going to be physical. He's done it two weeks in a row now and he needs to put it together for five and six and seven and then he'll become a really good player."

Timani can take another little step towards Test selection with a strong game against Carter, who finished the season as part of Australia's first-choice second-row pairing after earning man-of-the-match honours in his debut against France. A different style of lock to Timani, Carter is renowned for his high work-rate and strong set-piece skills; the 25-year-old among the Brumbies' best in both their outings against the Reds and Chiefs.

Another Rebels player looking for a big game will be back-rower Sean McMahon, who topped off a stellar 2014 with Wallabies selection under Cheika on the spring tour. Last year's Australia Under-20s captain came off the bench against the Barbarians before earning starts against Wales, France and England.

Scott Fardy has made a strong start to 2015 © Getty Images

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McMahon received his opportunity at No.6 through strong form but it was an injury to Brumbies back-rower Scott Fardy which opened the door. Somewhat of a late-bloomer, Fardy missed the spring tour because of a knee injury, cruelling his chances of making an early impression on the new Wallabies boss.

With his Waratahs side enjoying the round-three bye, Cheika will surely be keeping a close eye on Saturday night's match-up in Melbourne as well as the Queensland's clash with the Highlanders and the Force's showdown with the undefeated Hurricanes.

But the forward battle in Melbourne will perhaps carry the greatest interest, one Rebels coach Tony McGahan says his side can dominate by starving the Brumbies of the ball; a mission they achieved in the shock opening-round victory over the Crusaders.

"They've (Brumbies) got a blend of a good side that's been together for six or seven years," McGahan told Melbourne radio station SEN. "They're very systematic in their approach; they're very good at it and they don't give away a lot. So you really need to make sure you're in the grind for the whole game … and starve them of the ball."