The Australia batsman Michael Clarke admitted to a moment of panic after prematurely celebrating his maiden Test century at the SCG while a run-out decision was sent upstairs to the third umpire. The New South Welshman stole a quick single to bring up his three figures against South Africa, racing towards the members' area with his arms pumping triumphantly and apparently oblivious to the fact his stumps had been thrown down in a tight finish. A screen malfunction which delayed the third umpire relaying the not-out decision only added to Clarke's stress and there was no more relieved person in the ground when the green light finally flashed. It broke a perplexing run of outs at his favourite ground - four previous Test appearances failing to produce a half-century. "At the time I was confident but as I was carrying on like a goose I actually thought this is going to look real bad (if I'm out), but fortunately I just got home," Clarke said of his moment of uncertainty. "I'm obviously very happy to score my first hundred on my home ground as you would have seen by my emotions when I finally got there." Clarke started the day on 77 and sent the first ball he faced to the boundary. He was untroubled in reaching his century, going on to compile 138 before wearily belting a full toss back to the part-time off-spinner JP Duminy. "It's actually very disappointing when you have your family and friends come out and watch and you don't perform," Clarke said of his previous SCG failures. "I've let them down too many times so today I didn't let them down. "They were all here supporting so it's extra special." Australia went on to post 445 in their first innings, with the Proteas reaching 125 for one at stumps on day two of the third and final Test. Despite his bowlers taking just one wicket, Clarke declared that Australia are in charge of an intriguing Test match. "We're in a pretty good position. I think there is enough in the wicket that if we bowl well and stay patient we could be batting tomorrow afternoon," he said. "The wicket is going to get a little up and down so we have to come out and do the job with the ball and bat as well as we can in the second innings." *PA Sport