The Heat downed table-toppers Perth Scorchers by six runs in a nerve-jangler at Adelaide Oval on Tuesday to reach the playoffs.

Labuschagne made 46 in Brisbane's 6-181 and then took three wickets as the Heat survived a late Mitchell Marsh scare to prevail.

Marsh's Scorchers, assured a top-two finish regardless of the result, were on the ropes at 5-94 in the 14th over.

But Marsh blasted 54 from 26 balls and needed a six from the last ball to force the match into a super over - he could only bunt a low ball along the ground to midwicket.

"It was a bit of a rollercoaster," Labuschagne said.

"It feels great to actually get into the finals, we have been close the last few years.

"And it wasn't the perfect game today but that is also an exciting thing for us going into the finals - that we haven't put the perfect game in yet and we snuck in.

"We're a big threat."

Labuschagne (46 from 38 balls) and opener Chris Lynn (51 from 25) featured in a rapid 58-run partnership which underpinned Brisbane's innings.

Lewis Gregory (36 from 23 balls) provided some timely late impetus against a Perth attack headed by seamers Andrew Tye (2-23) and Jason Behrendorff (2-30).

The Scorchers' chase was on track early with openers Liam Livingstone (32 from 22 balls) and Jason Roy (41 from 32) putting on a 50-run stand from 31 balls.

Heat legspinners Mitchell Swepson (2-20) and Labuschagne (3-35) then stifled the Scorchers, who lost 5-41 to slip well off the pace.

Marsh produced a stunning late knock, smashing three sixes and four fours to revive his side.

Perth required 50 runs from the last three overs and Marsh took them to the brink of an unlikely win.

But Brisbane's Ben Laughlin held his nerve in the final over: Perth needed 17 to win and the wily paceman conceded just 10.

Australian Associated Press