Steven Smith will captain Australia's Test team for the rest of the series against India, with regular skipper Michael Clarke's career in serious doubt due to persistent injury problems.
Batsman Smith, aged 25 years and 195 days, becomes Australia's youngest Test captain since Kim Hughes who was named in 1979 at 25 years and 57 days, and the third-youngest all-time.
Smith was in a two-horse race with wicketkeeper Brad Haddin to replace the 33-year-old Clarke, who suffered yet another hamstring strain during Australia's victory charge on day five of the first Test in Adelaide on Saturday.
Haddin, who will deputise for Smith as vice-captain, had been seen as a viable short-term replacement for Clarke, but at 37 and in waning form with the bat, was not a long-term prospect.
Smith's selection ahead of Haddin suggests Clarke's hopes of leading Australia or even playing again remained in grave doubt, as Clarke himself suggested to reporters after Australia won the Adelaide test by 48 runs.
With Clarke sidelined, Smith could also be in line to lead Australia into the 50-over World Cup starting in February on home soil. The initial squad is due to be named on January 7.
Smith will be a popular choice as captain, a position dubbed the "second highest office" after that of the Prime Minister in cricket-mad Australia.
The right-handed batsman and part-time legspinner has scored a mountain of runs over the past 12 months and shown an impressive poise under fire at odds with his boyish features.