Michael Cheika admits he has `gone with his gut’ in backing Will Genia over Nick Phipps at halfback for the Wallabies’ World Cup opener against Fiji.

The former skipper had lost his grip on the No.9 jersey after battling serious injuries in recent years – and looked well behind when he suffered bone bruising and ligament damage in his knee during the stirring Rugby Championship win over the Springboks in July.

But far from hurting his World Cup chances, as was initially predicted, Cheika argues the time spent in recovery has sharpened the dynamic playmaker and made him an irresistible selection – even if Phipps pushed him all the way.

“I think that this set up with Genia starting, with his experience, being very sharp around the rucks (gave him the edge),” Cheika explained ahead of Wednesday’s showdown at Millennium Stadium in Cardiff.

“Maybe that little bit of time off and the operation (has him) looking very sharp with his running.

“Phipps has also been excellent as well – it’s been tough, but my gut tells me that’s the decision to make for this game.”

The Reds halfback will line up alongside NSW No.10 Bernard Foley, splitting the Super Rugby combinations that had been built up between Genia and Quade Cooper, and Foley and Phipps.

But Cheika said he’d never been one to select teams along state lines.

“I’m not a believer in that one,” he said.

“At international level, if one guy can’t pass the ball to another guy out in front of him … everyone else is playing in different teams together, so why can’t they?

“I think that is just narrowing our options down far too much.”

Cheika confirmed that Phipps would be the first-choice halfback for Australia’s second pool match against Uruguay, with the Wallabies set to field an entirely different starting side due to the four-day turnaround between games.

That will give the 26-year-old, who has been named on the bench against Fiji, two opportunities to showcase his wares.

“He’s a very effective player as I think we saw in the South Africa game when he came off the bench and lit the game up (with his) speed off the bench,” Cheika added.

Cooper, meanwhile, has been shielded from Fiji with a view to getting him ready for Uruguay.

Phipps, Matt Toomua and Kurtley Beale are the backline options named on the bench for Wednesday’s game.

“I just wanted him to concentrate on getting ready for the second game,” Cheika explained.

“He has been going very, very well at training.”