Wynne Gray: Oz halfback in his pomp ... five years ago

Will Genia (right) still has one of the sharpest brains on the field. Photo / Mark Mitchell

When the Reds were in their pomp, Will Genia was the best halfback in world rugby.

His impact was hypnotic and defenders stood off him in awe or rushed and left holes for his mind and reflexes to exploit. However, that was about five years ago.

Rugby has moved briskly since then and while Genia still has one of the sharpest brains on the field, damaged knees meant his frame could not keep pace. Cartilage problems bit into his impact for the Reds and Wallabies.

As the Wallabies suffered in that crucial role, the All Blacks found gold with the introduction of Aaron Smith, the livewire halfback whose talking matches his ever-ready actions. Pass, run, kick-they are all done at rare speed as he controls the rhythm and flow of the All Black game.

The All Blacks have risen and maintained an incredible run in the past four seasons while the Wallabies have wavered and wobbled. At times they have hissed and new halfback Nick Phipps was reliably steady and energetic but without that maestro flair. He was no Nick Farr-Jones, Ken Catchpole, John Hipwell or George Gregan.

Not in the vicinity of Genia either when he was in top form and now we get to judge whether there is any cha-cha left in the Queenslander's frame as he struts out tonight in Sydney to start the Bledisloe Cup and Rugby Championship series.

Coach Michael Cheika is either desperate or convinced because Genia has not played since the 2015 World Cup final as surgery and rehab have occupied his time. The experienced halfback has the all-clear to play and for Cheika that is a selection green light.

He wants more controlled direction, ingredients which were missing in the June test series loss to England and believes Genia will create that thrust for his side.

It's the old head against the thrusting Smith who is no new kid on the block.

He has played 50 tests since we were startled by his promotion to coach Steve Hansen's starting group.

Since then we have been amazed by most of Smith's test matches and he now sits near the top of the all-time All Black list with Sid Going, Dave Loveridge, Graeme Bachop, Chris Laidlaw and Justin Marshall.

Smith will see Genia's selection as a spur rather than a threat, the sort of challenge which lifts high quality rugby players to even greater levels.

There may be a calm authority about Genia's box kicking, passing, cover defence and variations but does he have the gas to snipe and challenge with his running game?

We did not see loads of that from Smith in the series win against Wales and tonight would be an arena to uncork that and take some of the glare away from Beauden Barrett's promotion.

Smith's box-kicking to quell Israel Folau's attacking instincts will be another piece of the halfback puzzle which will get the blood boiling in the annual transtasman rivalry.