Brisbane Heat 139 for 9 (Harris 39, Kerr 4-23) beat Sydney Sixers 127 for 8 (Bryce 30, Jonassen 3-24) by 12 runs

Brisbane Heat have continued to breathe life back into their WBBL campaign, landing a mega blow to the Sydney Sixers' campaign after beating the hosts by 12 runs.

In a crucial match for both teams, the Heat's bowlers delivered to restrict the Sixers to 127 for 8 at North Sydney Oval, defending their total of 139 for 9 with apparent ease.

Led by Jess Jonassen (3 for 24), the Heat remain fifth on the ladder with a 4-3 record after two straight wins.

The Sixers, however, are at risk of missing the finals for the second straight season with a 3-4 record while sitting sixth on the ladder. Even more concerning for the Sixers is the fact they were somewhatin control midway through the match.

While Grace Harris (39 off 26) and Georgia Redmayne (28 from 23) threatened to get away for the Heat, Amelia Kerr's 4 for 23 had the Sixers well on top.

The New Zealander spun her way through Brisbane's middle and lower order, while Sophie Ecclestone also claimed 2 for 18 from her four over.

But from there, it fell apart for the Sixers on a ground where runs are generally easy to strike. Alyssa Healy's difficult start to the tournament continued when she skied Shikha Pandey (2 for 25) in the first over, while Ellyse Perry also fell for one early.

Kerr became Pandey's second victim shortly after, and when Ashleigh Gardner was lbw trying to scoop Jess Jonassen, the game was all but over.

Sarah Bryce (30 from 26) and Ecclestone (24 not out from 18) threatened a late comeback, as teenager Caoimhe Bray also helped get the equation down to 29 off 12 balls.

But Pandey and Jonassen stood tall when it mattered in the final two overs to get the Heat home.

The other point of note for both the Sixers and Australia is the fitness of Healy. The 34-year-old opted not to keep on Thursday, with Bryce instead taking the gloves.

Healy has previously said she expects to be managed through the summer after a foot injury in the World Cup, with Thursday's move part of that.

"I've got a few things going on at the moment that I am managing," Healy told Fox between taking two catches at short third. "It's obviously a really big summer of cricket. I am still really confident I can bat, I just wasn't sure about squatting, which is one of the concerns.

"I am just trying to manage that, get through WBBL, we have six ODIs before Christmas and then the Ashes."