"He needs to take huge credit for the way the team's playing.
"In big games, I guess you rely on your big players, and there's no bigger player for us than Brendon McCullum."
Brisbane have not played BBL finals since beating the Scorchers in the 2012-13 final.
However, the return of West Indian leg-spinner Samuel Badree - the tournament's top-ranked bowler, according to the BBL's official player ratings - is a considerable boost against a Sixers side that has struggled against tweakers. "He matches up very well against a lot of their batters so a very key player for us," Burns said.
The Sixers clinched third spot on the ladder with a three-wicket win over the Stars last week, while the Heat let first position slip with a heart-stopping one-run defeat to the Melbourne Renegades.
Burns said the Heat will draw some harsh lessons from that match's manic finish. "Not just in the final over, but throughout the game we had opportunities to really run away with it," he said.
"Coming into semi-finals cricket, we know if the game's there to win, we have to not mess around and just win it."
A capacity crowd is expected at the Gabba, where the Heat have won just one of their four games this season - one of those losses coming against the Sixers.
"We've beat them up here, that's good for us," Sixers batsman Daniel Hughes said.
"But we just worry about what we're going to do.
"Brendon McCullum's their captain, he doesn't really know what they're going to do either - he's full of surprises.
"That's Twenty20 cricket, you can't plan too much."
- AAP
