Khawaja, Labuschagne and rain knock Thunder out

Usman Khawaja and Marnus Labuschagne emerged from T20 droughts with spectacular half-centuries before rain thwarted Sydney Thunder's hopes of chasing down Brisbane Heat's massive total in the BBL elimination final.

Kicking off the finals series, Khawaja and Labuschagne combined for a 128-run partnership to power Heat to the highest ever total at the Sydney Showgrounds.

Chasing 204, David Warner was in a belligerent mood with 36 off 20 balls to provide hope for Thunder before Sydney's temperamental weather reared in the seventh over with the home side eight runs short under Duckworth-Lewis Stern calculations.

Play was set to restart with Thunder facing a revised target of 90 runs off nine overs - they were already 52 for 1 after 6.5 - but the match was ultimately called off due to persistent rain.

Heat prevailed and meet Melbourne Renegades in a knockout final at Marvel Stadium on Sunday, while Thunder's see-saw of a season ended in disappointment.

Khawaja's impact for Heat since returning from Australia duty has mostly been through his captaincy, like when he helped guide inexperienced quick Spencer Johnson in high-pressure moments.

He had only averaged 16 in six innings in a disappointing start for his new BBL franchise. But against his old team, who he powered to the title in 2016, Khawaja showed his liking for the big stage and put the foot down after the drinks break with an assault on spinners Chris Green and Usman Qadir. He was unstoppable with a slew of innovative strokes, including reverse sweeps, to devastating effect, but his best shot was a gorgeous straight six off Qadir.

Khawaja fell short of a deserved century but his fluency seemed to rub off on Labuschagne, who had struggled with his timing as he played anchor before unleashing some inventive strokes of his own to notch his first BBL half-century in his 23rd innings.

Labuschagne, who had averaged just 16 runs with a strike-rate of 104, hit his first six of the season when he clubbed seamer Daniel Sams over long-on in the final over. He repeated the dose three balls later to lift Heat past 200 before his 48-ball 73 ended on the penultimate delivery of the innings. Labuschagne proved a point to critics that his formidable longer format batting can translate into T20 cricket.

Thunder were shorthanded without frontliner seamer Gurinder Sandhu, who injured his calf in his last game against Melbourne Stars. The 28-year-old Ross Pawson was thrown into the deep end with a debut in the elimination final.

Nathan McAndrew's struggles in the powerplay led to Pawson coming into the attack in the third over and he was immediately lined up. His first ball was carved through point for a boundary by Khawaja, who then smashed two short deliveries to the rope. A rattled Pawson then dished up a waist-high full toss to cap a 15-run first over in the BBL. He hoped his fortune might change when he returned in the 11th over but it only stirred the ruthlessness in Khawaja, who hit two sixes.

Pawson, who had earned his call-up through solid form in local Sydney ranks, did show glimpses of rapid pace but just couldn't get his length right and finished a tough initiation with 0 for 32 off two overs.

Unlike his mate Steven Smith, Warner had struggled in his long-awaited BBL return and averaged just 12.6 in five innings. But here, he started aggressively and took a liking to left-armer Johnson by smashing three boundaries in the fourth over. It was the best Warner had looked during this BBL season and he threatened to play a heroic knock before rain intervened to end Thunder's season.