Australia won the toss and elected to bowl, with the visitors looking to build on their 1-0 lead in the five-match series.
Kuhnemann and fellow spinner Mitchell Swepson have been rushed into the XI to help fill the void left by Ashton Agar, who injured his side during the series-opening ODI victory.
Paceman Jhye Richardson drops out of the XI to make way for the extra spinner.
Travis Head has been recalled for the injured Marcus Stoinis, who has been forced home with a side strain.
Sean Abbott (finger) and Kane Richardson (hamstring) are others who have already been sent home following injuries, while Mitchell Starc (finger) and Mitch Marsh (hamstring) could be ready in time for the third ODI.
Sri Lanka have lost star allrounder Wanindu Hasaranga to a groin injury.
He has been replaced by Jeffrey Vandersay.
Hasaranga snared 4-58 with the ball and scored 37 with the bat in the series-opening ODI.
Sri Lanka: Dasun Shanaka (capt), Danushka Gunathilaka, Pathum Nissanka, Charith Asalanka, Kusal Mendis, Dhananjaya de Silva, Chamika Karunaratne, Jeffrey Vandersay, Dunith Wellalage, Dushmantha Chameera, Maheesh Theekshana.
Australia: Aaron Finch (capt), David Warner, Steve Smith, Travis Head, Marnus Labuschagne, Alex Carey, Glenn Maxwell, Pat Cummins, Mitchell Swepson, Josh Hazlewood, Matthew Kuhnemann.
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