Brisbane Heat 169-8 (20 overs):
Sydney Thunder 125-9 (20 overs):
Brisbane Heat won by 44 runs.
Heat's Amelia Ker scored 48 to set Thunder a target of 170. England captain Knight scored 25 runs in reply but Thunder could only reach 125 in their 20 overs.
It's always nice to win these games and give ourselves a chance to win a trophy,.said Heat all-rounder Ker.
"It's exciting, when you come into these competitions you want to get there. It's going to be an interesting match and I'll see what happens." Batting first, Heat got off to a flying start, reaching 81 after nine overs. Both Ker and opener Grace Harris 45 fell short of half-centuries, but the wickets of Hannah Darlington 42 helped restrict the Thunder to 169. Lauren Smith and Sammy Jo Johnson also took two wickets each.
In reply, Sri Lankan captain Chamari Athapathu continued his impressive WBBL campaign with 41 runs, making him the WBBL's highest run-scorer (with 552 runs).
Despite a star-studded Thunder batting line-up, with top-order batsmen Tahlia Wilson, Phoebe Litchfield and Marizan Kap all falling cheaply, only Knight and Annika Learwood 21 were positive with the Thunder's bat.
Good bowling from Courtney Sepple 9 and Nicola Hancock 16 helped Heat to a 44 run victory, which took them to the challengers for the second consecutive year.
Brisbane take on the Perth Scorchers in Wednesday's challenger, with the winner taking on the Adelaide Strikers in Saturday's final at Adelaide Oval.