Perth Scorchers 147 for 9 (Allen 49) beat Sydney Sixers 99 (Smith 37, Beardman 3-20) by 48 runs

Ahead of a potential international debut, quick Mahli Beardman dismissed a rampant Steven Smith in a hostile bowling performance as Perth Scorchers defended superbly against rival Sydney Sixers to lock in a home final.

Chasing 148, after Finn Allen blasted 49 off 30 balls, Smith sped to 37 off 24 balls in the Qualifier but he played a lone hand on another seam-friendly Optus Stadium surface. Beardman was the standout of a disciplined Scorchers attack in what turned out to be a convincing victory with Sixers bowled out after 15 overs.

Sixers do have a second chance and on Friday will host the winner of the Knockout final between Hobart Hurricanes and Melbourne Stars.

It was the 10th final in an engrossing rivalry between powerhouse teams combining for eight titles.

Beardman turns match on its head

There was some surprise when Beardman was selected in Australia's squad for their upcoming T20I series in Pakistan ahead of the T20 World Cup. But he has long been identified as a prospect across formats having spent time around Australia's squad in the last 18 months.

Beardman is still emerging but has enjoyed a breakout BBL season marked by roughing up batters. He entered the attack in the fourth over with Sixers 21 for 1 but quickly turned the match with the wickets of Josh Philippe and skipper Moises Henriques with short deliveries.

Beardman ramped up to the mid-140kph region and bowled a consistent length to trouble the batters. He claimed the best wicket of his short career after a 139kph short delivery hurried onto Smith, who could not clear the fine leg boundary.

Smith continues to roll but lacks support

Unsurprisingly, given his rich vein of form and long domination of the BBL, Smith was the key to Sixers' chase. On his first delivery, the last ball of an opening over that had seen the stumping of Babar Azam, Smith skipped down the wicket and launched left-arm spinner Cooper Connolly down the ground.

It was the first time Smith hit a six on the first ball he has faced in a T20 innings but he struggled to get back on strike and faced just two more balls in the powerplay.

Sixers suddenly were in trouble at 23 for 3 and there was much interest whether Smith would go for broke or decide to play more conservatively. He emphatically answered and counterattacked recalled quick Brody Couch with a lovely square drive and a six over fine-leg.

But wickets kept falling and the pressure proved even too much for Smith, who could not thwart Beardman in a match-defining moment. Smith trudged off to mocked waves from an increasingly rowdy partisan crowd.

Starc, Allen shine after brief battle

After Henriques predictably sent Scorchers into bat, there was much anticipation over the potential fireworks of Mitchell Starc steaming into an in-form Allen.

Due to intense heat nudging 40 degrees Celsius along with the afternoon start on a working day, the terraces were relatively sparse and the atmosphere sedate compared to previous rollicking matches at the ground.

The game seemingly went through the motions with Scorchers watchful in a contrast to a pre-match belief that the surface would be batting friendly in a throwback to previous seasons.

Starc entered in the second over and once again made things happen quickly when he had Mitchell Marsh hitting straight to backward point where Lachlan Shaw took a terrific catch.

After a brilliant first over of 1 for 3, there was momentary concern for Starc after he clutched at his left shoulder having attempted a diving catch at midwicket.

Scorchers had trudged to 18 for 1 after 3.3 overs before Allen had seen enough and ramped a six off Starc, who responded with a fiery 148kph short delivery.

Having started with just 19 off 17 balls, Allen rediscovered his belligerent batting with a trio of blows into the crowd. He was on the brink of a third consecutive half-century before bottom edging a length delivery from Ben Dwarshuis onto his stumps.

Reshuffled Scorchers batting-order struggle against canny bowling

There was much spotlight on Connolly, who has bowled particularly well but been mired in a slump with the bat. Having earlier in the day received the Bradman Young Cricketer of the year prize, Connolly was shuffled down two spots to No. 5 and started with intent by blasting a second ball six.

But Connolly's struggles resurfaced and he sliced to backward point having made just 8 off 11 balls as Scorchers lost 5 for 34. Aaron Hardie returned to No. 3 having mostly batted with great effectiveness as a finisher this season but only made 17 off 19 having struggled to find the strike.

A well-disciplined Sixers attack executed slower deliveries to near perfection to ensure Scorchers struggled to regularly find the boundaries. Scorchers skipper Ashton Turner and Jhye Richardson did combine for a 44-run partnership to ensure the home side had a total that proved more than competitive.