Cricket Australia revealed on Monday that Clarke suffered the injury to his left shoulder during his unbeaten 161 against the world No.1 Proteas in the third Test in Cape Town, which further underlines the courage under fire shown by the Australian captain.

Although it is not yet known exactly when Clarke received the blow, which has seen him ruled out of the Sheffield Shield final on Friday, it is likely the injury happened during the fearsome barrage of bouncers he received from Morne Morkel early in his innings.

It was during this spell that Clarke was struck numerous times on his body, arms and helmet but despite being under immense physical duress soldiered on to post what turned out to be a series-winning century.

Clarke was even able to bowl five overs with the injury in the fourth innings as Australia pushed for victory on the final day.

The revelation is another shot in the arm to Clarke's reputation, which has flourished since Australia's 5-0 whitewash of England last summer.

The injury, however, means he will not be able to play for NSW in the Shield decider against Western Australia in Canberra.

“Michael Clarke was injured as a result of being struck on the left shoulder during the third Test against South Africa in Cape Town," said Cricket Australia physiotherapist Alex Kountouris.

"We have since done a series of scans that have demonstrated a fracture near his shoulder joint. We expect that this will heal with a period of rest. Michael is therefore unavailable for the Bupa Sheffield Shield final to be played later this week.”

Former Test bowler Mike Whitney said the innings that ruled Clarke out of the Sheffield Shield final was one that will long be defined for it's toughness.

"When I saw him this morning I gave Pup a hug and said 'that was phenomenal'," he said of Clarke's courageous innings. "He was going in to get it looked at and now we learn he had a fractured shoulder. To see what he went through it would have been easy for him to capitulate and no one would have asked the question.

"To not grab the armguard when the physio came out to check it - and I was sure he'd have grabbed one - and then to get one off the shoulder and into the jawline a couple of balls later  . . . that was reminiscent of the West Indies at their intimidating best and Morne Morkel at his best is very intimidating.

"For Michael to go on and make 160 after that, it was a heart breaker [for South Africa] as they'd just thrown everything at him - the kitchen sink, a 20 tonne truck and then tried to beat him with a stick - was a poignant moment. To go on and make 160 from that was phenomenal."