Australia have dominated the morning session on day two of the third Test against South Africa in Cape Town, reaching 434-4 at lunch.

Michael Clarke needed just eight runs for his ton at the start of the day, but he took 12 overs to get the century, with Steve Smith adding the majority of the runs early on.

The pair continued to add to the score before Dean Elgar caught Smith out with a short delivery, which the batsman hooked onto his stumps, ending his 84-run innings.

Clarke reached 137 not out by the end of the session, while Shane Watson added a quick 13 to place the tourists in a commanding position.