The Canterbury centre has moved from age' />

An irregular heartbeat has been, perversely, the source of Robbie Fruean's consistent form this ITM Cup.

The Canterbury centre has moved from age-grade star to potential All Black in the past eight weeks.

Not only is he the leading try-scorer with eight, Fruean has been a huge attacking influence, his pace and power proving difficult to contain.

He is arguably the form centre in the competition and, with Richard Kahui injured and out of action until next year, Fruean is in the frame for an All Black call-up.

At 1.92m and 108kg he has the physical presence to handle test football. He has also shown during the ITM Cup an improved ability to read the game; to pop up in the right places and attack the outside shoulder of defenders.

Fruean's improvement has been such, that the man who was largely responsible for bringing him to Christchurch from Wellington, Crusaders assistant coach Daryl Gibson, believes his protege could handle the step-up.

"I think he has been very good this campaign," says Gibson.

"I'd say alongside Rene Ranger, Robbie has been the form centre. He's a physical specimen and not only is he big, he's quick for his size. Robbie is explosive over the first 20 metres - from a standing start, he's very good and that makes him hard to stop.

"He's at university, he's a very good role model for young men and I think time in the All Black environment would really benefit him. If you look at centres across the country then obviously Conrad Smith is the number one with the likes of Rene, Sonny Bill Williams and Robbie all contending."

At the core of Fruean's improvement has been a medical and training regime that was struck upon by accident.

Fruean had been selected to play the opening game of the campaign against Hawke's Bay but had to withdraw because of an irregular heartbeat (arrhythmia) in the build-up to the game.

He was put under surveillance - Fruean had heart surgery in 2008 after contracting rheumatic fever - and his medical team opted to try a different drug regime.

The change in medication has been a revelation and Fruean's heart is now operating close to full capacity as opposed to the 50 per cent it managed during Super 14 - which was why he tended to fade midway through the second half.

He's also embarked on a new conditioning regime where he runs for longer at a slower pace which has strengthened his heart and given him a better conditioning base. He's fitter with improved aerobic capacity and that has been a factor in his growing confidence.

"Robbie missed a year of training when he was ill and that put him a bit behind. He's been playing catch-up," says Gibson. "But he's put a lot of rugby under his belt in this campaign and he's getting his body right.

"I also think he's coming to grips with what it means to be a professional. He's by no means the finished article. He has been working hard on his weaknesses but there is more to do. He's definitely on the right track."

With only two weeks until the All Black squad is announced, there is not much more Fruean can do to push his case. His chances of inclusion have risen on account of Kahui's non-availability and by confirmation only two halfbacks will travel.

There is a growing belief three first fives - Dan Carter, Aaron Cruden and Colin Slade - will be selected, that Sitiveni Sivivatu will return and that Sonny Bill Williams will be too hard for the selectors to resist.

Piri Weepu, Jimmy Cowan, Ma'a Nonu, Conrad Smith, Cory Jane, Israel Dagg and Mils Muliaina are bankers which means in all probability a group containing Fruean, Joe Rokocoko, Ranger, Isaia Toeava, Zac Guildford, Hosea Gear, Ben Smith, Luke McAlister, Jared Payne and Benson Stanley are competing to fill two places.

The final mix will depend on the balance the selectors want to strike; how they view the utility talents of Ranger and Toeava in particular; whether they feel they need a ball-playing tactical option at second five and whether they feel Rokocoko's form has been too good this year to discard in favour of experimenting with Fruean.

Maybe the competition is too fierce for Fruean to force his way into the national set-up this year - but at least he has shown selectors he has the heart for it.