At his best Karunaratne is one of the finest batters in world cricket, able to ebb and flow with the tempo of a game.
His current status as No.6 in the ICC Test rankings is proof of that, with the left-hander having averaged 60.8 in the past 18 months.
But he is also the Sri Lankan with the most to prove in the next fortnight.
He averaged a miserable 6.83 in 2016, as Starc removed him five times in six innings before backing it up with two more dismissals in Canberra in 2019.
Six years ago, Starc beat him with pace early in the series before having him play at balls he shouldn't have for scores of 5, 0, 0, 7, 7 and 22.
Realistically Sri Lanka now need the opener and captain to stand up if they are to reclaim the Warne-Muralitharan Trophy.
In general, the Sri Lankan team he leads find themselves at an interesting juncture.
Gone are the household names from eras past, when the likes of Muttiah Muralitharan, Sanath Jayasuriya, Aravinda de Silva, Chaminda Vaas, Kumar Sangakkara and Mahela Jayawardene were the best in their class.
Even the two stars of their 3-0 rout of Australia in 2016 have both moved on, with spinners Rangana Herath and Dilruwan Perera having since retired.
To many Australian fans, there is an element of the unknown around Sri Lanka's Test team.
Red-ball series between the two nations are infrequent, while Wednesday's match will be the first televised in Australia from Sri Lanka since August 2019.
But this is not a Sri Lankan team without stars.
While Karunaratne is the key up top, veteran Angelo Mathews enters in form off the back of scores of 199 and 145no in Bangladesh last month.
Dinesh Chandimal was just as potent on that tour, and remains a threat on the sub-continent despite struggling on the bouncier wickets of Australia three years ago.
Dhananjaya de Silva also has reason to enter believing he can be a force, starring as a rookie in 2016 with the bat while also being able offer turn with the ball.
What Sri Lanka need is support around that quartet.
Lasith Embuldeniya is now the country's chief red-ball spinner, but had his own issues on what should have been friendly wickets for him in Bangladesh.
Praveen Jayawickrama and Ramesh Mendis will be his likely back ups, while players of the future in Dunith Wellalage and mystery spinner Maheesh Theekshana are yet to debut.
Asitha Fernando and Kasun Rajitha lead the pace attack, with just 16 Tests between them.
At least one of those bowlers must channel Herath and star if Sri Lanka are to repeat their 2016 heroics.
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