Rugby:Australia flanker David Pocock is fit and firing ahead of tomorrow's World Cup quarter-final against South Africa in Wellington.

The 23-year-old missed the Wallabies’ 15-6 loss to Ireland and 67-5 win over the United States with a back injury.

He was the Australians’ best performer in his comeback match against Russia last Saturday, scoring two tries and dominating the breakdown before being replaced at half-time as a precaution.

“I’m feeling good. I felt really good against Russia and I was really keen to play on but I watched the second half and trained pretty good this week,” Pocock said. “I’ve done everything so I’m good to go.”

Wallabies scrumhalf Will Genia said Pocock’s importance to the team could not be understated.

“He makes a massive difference. He’s very important to the side because he puts pressure on their breakdown and he’s very effective at getting us quick ball because he is so good in that contact area,” Genia said.

“Watch the team play when he’s not there and when he is there. He makes a huge difference to the side.”

Pocock is well aware of the challenge he faces against Springbok Heinrich Brussow in the sudden-death encounter. But while he rates his direct opponent highly, the Western Force man said it would take a collective effort to win the breakdown against a “balanced” South African backrow trio that also includes Pierre Spies and Schalk Burger.

“He’s right up there. He’s very good at what he does and I think the support he gets from Schalk and Pierre really helps him do what he does,” Pocock said of Brussow.

“I don’t think it’s me against him — it’s more a team thing when it comes to the breakdown.

“It’s such a huge part of the game and the team that does produce fast ball and slow down the opposition’s ball it goes a long way to securing the victory.

“If you look at the South African backrow, it’s probably the most balanced in world rugby at the moment.

“They all bring something different and they’re all outstanding at what they bring so it’s going to be a huge challenge for our backrow and our team to counter that.”

Meanwhile, utility back Berrick Barnes completed a short and sharp captain’s run in windy conditions today and will take his place on the bench after overcoming a virus.

“He’s good. He came to dinner with us last night and trained well today and he says he’s feeling good which is good,” skipper James Horwill said.