Jonassen stars as Heat lock in finals berth

A star turn from spinner Jess Jonassen has lifted Brisbane Heat to a 22-run win over Sydney Thunder and into the Weber WBBL finals.

Chasing Brisbane's 8-160, the Thunder managed 9-138 with Jonassen snaring four wickets in Friday's fixture at Adelaide Oval.

Brisbane's victory in their last minor-round game ensures they reach the playoffs - they're now in third spot on 16 points.

The Thunder are fourth on 15 points with one game remaining, two points clear of fifth-placed Hobart Hurricanes who also have one match left before the finals.

But the Hurricanes would need a massive win over ladder leaders Adelaide on Sunday to boost their run-rate ahead of the Thunder, who meet the Sydney Sixers in their last game before the finals.

The Adelaide Strikers (18 points) meet second-placed Perth Scorchers (16) on Friday night.

The Heat's Jonassen was pivotal in Friday's win, taking 4-26 from her four overs.

Thunder openers Chamari Athapaththu (34 from 28 balls) and Phoebe Litchfield (23 from 21) gave the Sydney-siders a brisk start.

But the Thunder then lost six wickets in an eight-over span to lose momentum as Jonassen turned the screws.

Earlier, Brisbane's Beth Heath made 29 from 25 balls to top score during an even batting effort.

Seven batters made more than 12 with opener Georgia Redmayne (21 from 21), Amelia Kerr (20 from 17) and Laura Harris (19 from nine) making handy contributions.

Brisbane's innings finished with a flourish as Georgia Voll smacked a six in her rapid-fire 18 not out from only eight balls.

Thunder quick Sammy-Jo Johnson was the chief wicket-taker with 3-39 while Marizanne Kapp claimed 2-26.