These are crunch weeks for Ma'a Nonu, who right now is coming a long second to Mils Muliaina in the race to replace Tana Umaga in the All Blacks.

Nonu and the Hurricanes play the Highlanders today and then follow that up against the Brumbies, Chiefs, Reds and Waratahs.

The matches against the Australian teams are both away games and, I'd suggest, Nonu's main chance against international opposition such as Stirling Mortlock and Morgan Turinui to show that he is definitely the man for the No 13 jersey for the season.

However, even an old prop can see that Muliaina is ahead at the moment. He is a more accurate, consistent player who feeds his outsides better than Nonu - who remains a very dangerous attacker, especially close to the line.

But while Nonu will score tries that no one else can, he is not so good at giving the ball to others for them to score.

There are other question marks over his ball security and defence and my pick is that Muliaina will be at centre alongside Daniel Carter and Aaron Mauger, with Leon MacDonald playing superbly at fullback.

I can't see any bolters at centre - Caleb Ralph and Casey Laulala don't seem to be in the frame these days, although it was interesting that Ben Atiga played at 13 instead of the rotated Anthony Tuitavake for the Blues against the Force on Friday.

Tuitavake probably hasn't done enough this year but they might be a bit interested in Atiga as he can cover fullback as well. However, I'd see it as Muliaina in the run-on team and Nonu on the bench.

The situation at halfback might be a bit more interesting, although, as a whole, there will be few changes in the All Blacks this year unless forced by too many injuries in one position.

Byron Kelleher, up until last night's game against the Stormers, is only the number three halfback in New Zealand, behind Piri Weepu and maybe Andrew Ellis of the Crusaders.

There are signs that Kelleher is on the way back and we mustn't forget the old saying that form is temporary and class permanent. But, before he came on for that second half against the Highlanders a couple of weeks ago, he hadn't offered much and I think both he and Jimmy Cowan had been way off the pace.

Weepu has been handled well by Colin Cooper and Murray Roulston and they have rested him correctly and brought on Brendon Haami at the right times.

Even Weepu has been sound and consistent but that's all.

As for Ellis, I can remember Robbie Deans explaining why he wanted Kevin Senio in the Crusaders - because he was an experienced halfback and he had both Jamie Nutbrown and Ellis left after Justin Marshall headed to the UK.

It was a fair call and Deans is still playing it as a horses-for-courses thing with his halfbacks.

But Ellis does look very good and, once you give a youngster like that a go, they often take off.

As for the Highlanders halfbacks, I rate Chris Smylie but Cowan has been getting the starting jumper lately.

Of course, in All Black terms, it is early days yet and there is time for these guys to run into the sort of form that will have Graham Henry nodding his head.

There is also the fact that experienced players like Kelleher do lift for the big ones.

But, with the substitutions as they are these days, the second choice halfbacks also get a great shot at running into real form.

In the old days, the second choices stayed on the bench but now they can show their stuff quite clearly.

I'll be watching the halfback spot closely in the coming weeks as I reckon it will be one of the most closely contested.