David Warner fired and Pat Cummins did his job with the ball but Australia are still some way from clicking in the World Cup following their 41-run win over Pakistan.
After Warner's 107 helped Australia to 307, the defending champions survived a scare to have Pakistan all out for 266 in the 46th over.
But while the victory margin made it sound simple, the reality was anything but.
Cummins appeared to have Pakistan reeling at 6-160 after he took the key wickets of Imam-ul-Haq (53) and the dangerous Shoaib Malik (0), finishing with 3-33.
But Pakistan's lower order had other ideas, with first Hasan Ali (32 from 15) and then Wahab Riaz (45 off 39) putting their team back in the game.
With the equation down to 44 off 35 and three wickets in hand, Starc (2-43) removed Wahab and Mohammad Amir in the same over to end Pakistan's hopes.
His dismissal of Wahab was to some degree fortunate after the Pakistani was given not out to a caught behind appeal on field, before captain Aaron Finch reviewed with one second left on the countdown clock.
Replays showed the ball that had just nipped away from him brushed the edge of the bat to have him out, before Starc then bowled Amir two balls later.
Glenn Maxwell then finished the job, producing an acrobatic run out of Sarfraz Ahmed (40) the following over.
"It got closer than we would have liked," Cummins said.
"We probably gave them a couple with a bit of width and a bit too full at times. And they batted quite well and were suddenly back in the game."
Nathan Coulter-Nile was improved with the ball to finish 1-53 while Kane Richardson took 2-62 in his World Cup debut.
If Australia had lost the game, they would have been left to rue the end of their batting innings after they looked set for a score closer to 400.
The Aussies fell from 2-223 in the 34th over to be all out 307 some 15 overs later.
Warner's century had marked his first since he returned to the Australian side from his 12-month ban, as he dominated on the drive and punished Pakistan's bowlers whenever they erred in their length.
His 111-ball knock also answered questions about his scoring rate in emphatic fashion, as he and Finch (82) combined for a 146-run opening stand.
But after Glenn Maxwell (20) threw his wicket when he was clean bowled trying to go big, Shaun Marsh (23) and Usman Khawaja (18) both struggled to get going before falling to left-armer Amir (5-30).
"I still think I left a lot out there," Warner said.
"You know, 70 balls to go. And with the weather, trying to build partnerships again, I probably hold responsible for the way we fell apart there."
The result puts Australia second behind New Zealand, with England and India in third and fourth but with games in hand.