Brisbane Heat and Sydney Sixers have been left pondering the sizeable batting holes of their departed Test players ahead of Thursday's clash at the SCG with a grand final spot up for grabs.

The Heat trio sparked a resurgence with the team winning six of their last seven matches after being mired for much of the season near the bottom of the ladder.

They each made important contributions in finals victories on the road against Sydney Thunder and Melbourne Renegades to have Heat positioned for an unlikely tilt at a second BBL title.

Once part of a devastating opening partnership with Chris Lynn, big-hitter Bryant failed to fire from seven matches this season and averaged just 15.71.

The 27-year-old Heazlett has not played this season, but the bright finals lights shouldn't faze him having mustered 48 BBL matches over the past seven seasons.

"We have lost some of our Australian players but the guys we are bringing in have played the format before so I don't have a problem with it," said Heat coach Wade Seccombe. "They have performed when they came in."

Sixers don't have as many holes to fill, but nonetheless need to replace Smith, who lit up the BBL with ballistic batting marked by consecutive centuries.

"We've played 10 games without Steve and had a few wins along the way so we're familiar with this group," said veteran batter Jordan Silk, who re-signed with Sixers on a three-year deal.

"[Hughes] has trained well, he's been great around the group all year. He's probably one of the more unlucky players in the competition to not be playing," Silk said. "He's been a reliable performer at the Sixers for a number of years."

"[Kerr] is a vital piece for us down in that middle to lower order," Silk said. "Whether we'd see his value at the top in a game like this, I'm not sure what'll happen there. He's almost been probably too good at the role he's played at six to warrant moving him."

As they eye a seventh grand final appearance, Silk said Sixers would target Heat's new-look batting line-up.

"They have some big holes from a batting sense," Silk said. "Looking back to the game at the Gabba, where they were without those [Test] batters, [Josh] Brown and McSweeney stepped up. Queensland produce very good cricketers. We will do our research so we can stop them."

The winner plays Perth Scorchers on Saturday at Optus Stadium with a crowd of more than 50,000 expected.