The Gabba (Brisbane), Dec 17 : Left-handed batter Travis Head's emphatic unbeaten 78 helped Australia get a marginal edge over South Africa on the opening day of the first Test, here on Saturday. After South Africa were knocked over for 152 on the stroke of tea, Australia found themselves in the same strife and were reeling at 27 for 3 before Head's blazing knock and his 117-run fourth-wicket stand between with Steven Smith, took them to 5-145 at stumps. It would have been a more emphatic advantage to the hosts had Smith and night watch Scott Boland not lost their wickets in the final two overs as Proteas quick Anrich Nortje pushed above 150kph. Beginning the day, Australia's opening bowlers were wayward upfront, often bowling too short and unable to maintain a consistent line. However, they still got rewards as Mitchell Starc got rid of Elgar with a down the leg side delivery and Pat Cummins forced Rassie van der Dussen to nick off the ball. But it was Scott Boland, who really rocked South Africa. He had Erwee caught low down by Cameron Green in the gully and in the same over had Khaya Zondo lbw to a delivery that hit him on the back pad, reducing South Africa to 27 for 4. From there on, the responsibility was on Bavuma and Verreynne to bail out visitors from the trouble and they did that to an extent. Their 98-run stand was built on Verreynne's aggression against the short ball and Bavuma's patience but that ended when Starc returned for a third spell to remove Bavuma. Verreynne brought up his fifty but he didn't get support from the lower order batters as South Africa went on to lose five wickets for 20 runs in 52 balls, including three to Nathan Lyon, who removed Marco Jansen, Verreynne and Anrich Nortje. In between, Starc picked up his 299th Test wicket when he set Keshav Maharaj up with a bouncer and then had him caught at slip off a full ball. After getting bowled out for a low total, South Africa's bowlers kept them in the contest with statement opening spells. Kagiso Rabada started with a snorter of a short ball to dismiss David Warner. Jansen too struck with his first ball and had Marnus Labuschagne stuck in the crease and caught at second slip. In the next over, Nortje got rid of Usman Khawaja. But, Head played his natural fast-scoring game and raced to a 48-ball fifty. On the other hand, Smith also provided steady support before he was bowled by Nortje with less than five minutes to the close.Boland was sent in as nightwatcher and lasted only four deliveries before he edged Rabada to Verreynne. Brief scores: Australia 145/5 (Travis Head 78 not out; Anrich Nortje 2-37, Kagiso Rabada 2-50) trail South Africa 152 (Kyle Verreynne 64; Nathan Lyon 3-14, Mitchell Starc 3-41) by 7 runs. /IANS