Ben Dwarshuis has again proven the Sydney Sixers unlikely hero with the bat, coming in late to lead them to a final-ball win over the Thunder.

On the same night Sam Konstas was bowled for a duck in his last innings before a likely Boxing Day Test debut, Dwarshuis hit the Sixers home at Engie Stadium on Saturday.

Chasing 164 for victory, the Sixers looked shot when they needed 47 from the final four overs.

But Jordan Silk (36no from 25) helped them take 17 from a Nathan McAndrew over, before Dwarshius provided the late heroics with 20no from eight balls.

After launching Lockie Ferguson for six from the first ball he faced, the Sixers quick then took charge with 15 needed from Chris Green's final over.

Green's first three balls were hard to get away but he was hurt by two straight wides outside off.

Then with seven needed from two balls, Dwarshuis smashed Green over the long-on rope for six, before taking a quick single off the last ball to seal the win.

It came after Dwarshuis also hit 14no from six on Monday night to help the Sixers beat the Melbourne Renegades.

"One of the attitudes we have in this team is to win from any position," Dwarshuis said.

"Coming in first ball is something in my role I practice, trying to hit the first one for six. So it was nice to do it tonight, especially against Lockie, one of the world's best."

Earlier, Cameron Bancroft hit an unbeaten 70 from 52 balls to help the Thunder reach 5-163.

Favoured to return to the Test team a few months ago, Bancroft has been overtaken by both Konstas and Nathan McSweeney this summer with only three scores above 20 in 18 innings before Saturday.

But he looked back in good touch against the Sixers, taking to spinner Joel Davies and peppering the backward-square boundary off Dwarshuis.

His innings helped keep the Thunder's innings together, as Oliver Davies also banged 47 from 34 for the hosts and hit three straight sixes off Todd Murphy.

Meanwhile, the duck for Konstas came in what will be his last innings before a likely Test debut at the MCG on Boxing Day.

Playing for the first time since being called into Australia's Test squad, Konstas went to cut a shot ball from Akeal Hosein and bottom-edged onto his stumps.

Konstas said axed Test opener Nathan McSweeney had been among the first to congratulate him, following an initial call from chief selector George Bailey.

"I was so thrilled and called my parents straight away, and they were very emotional," Konstas said on Fox's BBL coverage.

"Mum was in tears, so I was trying not to cry. Dad was super proud. It's been an amazing journey with all the ups and downs.

"I'm very excited. I want to be challenged and I've got a few plans against India's bowlers. I feel like I'm moving really nicely so hopefully I get that opportunity."