All five Australian bowlers claimed wickets with Mitchell Starc taking three for 43 while his new-ball partner Josh Hazlewood took two for 18 from eight overs
Hetmyer's 61 off 36 balls with four sixes and two fours paced the home side to 196 for four after they were sent in to bat yet again by visiting captain Aaron Finch
However Gunathilaka's demise to pacer Alzarri Joseph for 36 triggered a gradual decline to 151 for six with left-arm spinner Akeal Hosein taking three for 33 while Jason Mohammed snared his sixth wicket of the series by bowling Karunaratne for 31.