It was hard to wipe the smile off Pat Cummins' face at the end of the first day of this Test, when he had taken one wicket. On the fourth day, his grin seemed as permanent as Hashim Amla's beard.

At 18, Cummins had become the second-youngest man in Test history to take a six-wicket haul, behind Bangladesh's Enamul Haque jnr. He had been on a hat-trick. He had outbowled his more senior colleagues. Most importantly, he had given Australia a fighting chance of victory in a match that 24 hours earlier appeared to have slipped from their grasp.

And all this from a man who began the year uncapped at state level.

"It's surreal to be overseas playing cricket for Australia," Cummins said. "To be in the position where we can win a game is certainly special as well."

By the close of play, Australia were 168 runs from what would be a series-levelling win. Were it not from the way Cummins bowled either side of lunch, they would have next to no chance.

First, there was the outswinger that got rid of AB de Villiers, full enough to encourage the drive and curvy enough to catch the edge. It ended a 147-run stand between de Villiers and Hashim Amla, a partnership that threatened to take the match out of Australia's reach.

After lunch, Cummins struck first ball when a fierce bouncer clipped Vernon Philander's glove on the way through to Brad Haddin. A yorker accounted for Morne Morkel next ball. As Cummins stood at his mark, on a hat-trick and bowling to Imran Tahir, his aim was simple.

"A couple of the guys said Tahir wouldn't be the worst batsman to bowl a hat-trick ball at," Cummins said. "I was just trying to bowl it as quick as possible and as full, and at the stumps. Unfortunately he fended it away."

It was a fine ball, for a hat-trick delivery: full and straight. He finished the innings with 6 for 79 when Dale Steyn edged behind. It completed a brilliant debut bowling performance from Cummins, Australia's second-youngest Test player of all time.

It was all the more remarkable considering the expectations that have been placed on Cummins. He entered the match with a reputation that belied the three first-class games he had to his name. Cummins said playing away from home had been a blessing, although it was still daunting at first to bowl to men like Amla and Jacques Kallis.

"Just knowing what the batsmen are capable of here, you see them on TV and you've heard about them, the big averages come on the scoreboard," Cummins said. "It is more daunting but once you get into a spell you start to forget about those things.

"You're removed from a few of the pressures that Australia give you and the attention that you get over there. That's helped, and also having a team that I'm pretty familiar with. We've been here for almost a month and a half, so I'm hanging out with the same bunch of guys."

He'll be hanging out with them for a while yet. Cummins has become a certainty for Australia's first Test of the home summer, against New Zealand on December 1 at the Gabba. The only doubt is how his young body will handle a full season of Test cricket.

That's a question for another day. For now, Cummins deserves to be celebrated.