After maiden Test ton, Carey jokingly thanks Kevin Sheedy for rejecting him at AFL side GWS Giants

After scoring a brilliant hundred in the second Test against South Africa, Alex Carey paid tribute to AFL legend Kevin Sheedy.

On day three of the second Test against South Africa at the MCG, the 31-year-old made an errorless 111 as Australia declared on 575-8, closing in on an unbeatable 2-0 series lead.

Even though Carey had hoped to make history at Melbourne's famous venue with a Sherrin in his hands rather than a cricket bat as a child, it was still a special moment for him.

Carey was the first captain of GWS when they participated in the under-18s competition in 2010. He played both football and cricket throughout his teenage years.

He was advised by Sheedy, however, that he should devote himself entirely to cricket because he was too slow for the demands of professional football when the Giants made their AFL debut.

"I have to thank Kevin Sheedy it was a Test hundred rather than a run around with GWS on the footy field, he pointed me in the cricket direction," Carey told the Sydney Morning Herald on Wednesday.

When it became clear that Carey had made the right career choice, Sheedy, who led the Giants in their first AFL season, jokingly threatened to send Carey an invoice for his services.

"I'll send him an invoice with 10 per cent as manager of his performances after I told him cricket should be the game for him," he said. 

"It's a sensational achievement. I'll be honest, I didn't know if he'd ever be as good as he has become."

"He made the right decision. Everyone at the Giants always knew he would do something, but we weren't sure it would be in the AFL."

Carey took up wicket-keeping after being released by South Australia after three Sheffield Shield matches and eventually made an impression for Australia in white-ball cricket.

He is also the first wicketkeeper to reach a century in a Test match for Australia since Brad Haddin made 118 in the second Test of the 2013–14 Ashes at Adelaide Oval.

Among the 34 players who have kept wicket for Australia's men's Test team, Carey's Test average of 34.80 is second only to Adam Gilchrist's in terms of overall average.

"I'm extremely proud. It's been, I guess, a bumpy journey along the way - footy not working out and cricket not working out after a few games," Carey said.

"I never gave up the hope of playing sport at the highest level and continued to try to chase that goal and dream.

"Hopefully there's a bit more to come and that's done with a lot of support around."

"It's one of those things - never give up on what you want and hopefully it comes. I'm just lucky that it has come my way," Carey concluded.