The unusual net session that recalibrated Starc mid-Test

After bowling almost a quarter of Australia’s 101.5 first-innings overs to Pakistan in the first Test, Mitchell Starc had earnt the right to put his feet up when the final wicket was taken on Saturday afternoon.

At the very least, Starc might ordinarily have jumped into an ice bath after a long stint in sweltering heat. The pitch was yet to break up and another heavy bowling load in the second innings loomed.

So the left-arm spearhead's decision to instead dart straight out to the Perth Stadium practice nets to continue bowling marked a deviation from the norm.

Andrew McDonald and Daniel Vettori went scurrying after him.

Starc, frustrated his attempts to self-diagnose a technical concern that had caused him to become increasingly wayward, was adamant he needed to fix his issues there and then in the hottest part of the day.

Compounding things were troubles with where he jumped into his bowling action from the southern end of the ground (his 'take-off' point happened to be exactly where the drop-in surface met the outfield), as well as a dip in the pitch where his front foot was landing when he bowled from the other end.

As any fast bowler would attest, fears of slipping while jumping or landing during their bowling action can derail even the most confident speedster.

It was with all that in mind that Starc had bowled a series of wide and off-target deliveries leading into and after Australia took the second new ball on day three, a departure from the increasingly reliable version of the paceman captain Pat Cummins has relied upon in recent times.

In Test cricket this year, only Stuart Broad (38) has more than Starc’s 34 wickets.

McDonald, who'd had a long discussion with Starc on the ground at stumps on day two after the bowler's concerns first emerged, and bowling mentor Vettori had been trawling through footage of Starc’s deliveries trying to narrow down the root cause of his troubles.

Starc wanted to figure it out himself.

"I like to think I'm experienced enough to be able to problem solve and work it out on my own," Starc told cricket.com.au.

"That probably frustrated me a little bit out there in the first innings – I couldn't quite work out what the issue was.

"I came off and had a quick look at some footage. Then once the innings finished, I had probably a dozen balls out the back just trying to work it out, along with Dan Vettori and Ronnie (McDonald).

"I sort of worked out what it was. (The net session) was just to reassure that's what it was, and that I'd fixed it."

Starc had misdiagnosed himself in the first instance.

The 33-year-old thought his front (right) arm had been falling away, which was why he was dragging balls down towards the right-hander's leg-side.

What Starc, McDonald and Vettori realised was the issue was in fact something else completely; his bowling arm was not following an 'up and down' motion, triggering a chain reaction that meant he was struggling to hold a consistent line.

Sometimes it only takes one faulty part to throw off a finely calibrated engine. The upside was Starc did not need long with the mechanics.

Twelve balls in the nets and he was good to go again.

A day later, Starc took the first over and was on his mark from ball one. It only took six to find a flaw in Abdullah Shafique's rock-tight technique. He finished with the scalps of three of Pakistan's top six and might have had more if wickets did not keep tumbling down the other end.

The effect of his devastating spell on day four was lost amid his close mate Nathan Lyon surging to 500 Test wickets.

But there is a quiet optimism in the Australian camp that Starc will be even better when the second NRMA Insurance Test rolls around on Boxing Day at the MCG.

"It's part of being a cricketer – you're in this game long enough, you hopefully work out a few things, or be able to problem solve on the go," said Starc, who returned match figures of 5-99 from 31 overs.

"I've been around a long time and had to work through a few things. It was more of a feel thing and being able to work out what wasn't quite working the way it wanted to be.

"It's what we're after as a group of experienced cricketers to problem solve on the go, and that's why we've been pretty successful in the last couple of years."

NRMA Insurance Test series v Pakistan

First Test: Australia win by 360 runs

Second Test: December 26-30, MCG (10.30am AEDT)

Third Test: January 3-7, SCG (10.30am AEDT)

Australia squad: Pat Cummins (c), Scott Boland, Alex Carey, Cameron Green, Josh Hazlewood, Travis Head, Usman Khawaja, Marnus Labuschagne, Nathan Lyon, Mitch Marsh, Steve Smith, Mitch Starc, David Warner

Pakistan squad: Shan Masood (c), Aamir Jamal, Abdullah Shafique, Abrar Ahmed, Babar Azam, Faheem Ashraf, Hasan Ali, Imam-ul-Haq, Khurram Shahzad, Mir Hamza, Mohammad Rizwan (wk), Mohammad Wasim Jnr, Noman Ali, Saim Ayub, Salman Ali Agha, Sarfaraz Ahmed (wk), Saud Shakeel and Shaheen Shah Afridi