South Africa have been issued a warning by injured Australian quick Mitchell Starc about wandering far out of the crease following an almost-Mankad incident during the Boxing Day Test.

Starc was left perplexed and annoyed after Theunis de Bruyn's inability to stay in his crease during the course of his deliveries.

Skipper Pat Cummins has now given the team permission to execute the controversial dismissal if the Proteas continue to wander out of their creases.

Named after India's Vinoo Mankad in the late 40's and although totally legal, the Mankad is often frowned upon as a breach of cricket etiquette and sportsmanship.

RELATED: Is the Mankad a question of culture?

Regardless of its perception, Starc was justifiably frustrated, issuing de Bruyn with a stern talking to.

“Just stay in your crease. It's not that hard,” Starc was heard saying through the stump microphone. “The line's there for a reason mate.”

Post-match Starc had the same message.

“I had a word to him last night because he was doing it yesterday. He was halfway down Punt Road when I stopped,” Starc said.

“Then I said it again to him. He said, ‘I'm not doing it on purpose'. Gee, I've got to keep my foot behind the line so you can at least keep your bat behind the line. There's no need for it. I keep saying I'm not going to take the stumps, but you can at least keep the bat behind the line.”

“That's just absolutely taking the mickey,” Starc said.

“That's not just taking off before I've bowled, he's a metre down the wicket. I gave him a couple of warnings, if he wants to keep doing it I'll take them.”

The International Cricket Council has altered the perception of the play by changing the mode of dismissal to “Run Out”, as opposed to “Unfair Play”.

Starc even suggested earlier in the summer that the same punishment should be handed to batters with a docking of one run.

With less stigma, the warning and the green light to Mankad from Pat Cummins in the third Test, we could see a rare form of dismissal.

The third and final Test will commence January 4th, starting at 10:30am AEDT.