Going into this weekend's Women's Big Bash League semi-finals, Mooney and Harris form the competition's fastest-scoring opening combination when they take on the Sydney Thunder at Drummoyne Oval on Saturday.

Harris has hit 356 runs at a strike-rate of 153.44 in the competition, while Mooney has also cruised along with 407 runs at 126.

Given freedom to hit out at the top without consequences, it makes them a serious threat to the Thunder who were never really challenged for a finals spot before finishing second.

"I think that's the job of the opener to get the team off quickly but to not let it affect the group if we both get out early," Mooney said.

"Everyone has contributed this season and stood up at different times so I think that's made the biggest difference."

And while Mooney isn't quite ready to take on the Bash Sisters term - reasoning that Grace already has an actual sister in their side in Laura - it's a worthy description.

Harris is known as one of the hardest hitters in the country, her record-breaking WBBL-fastest 42-ball century against the Melbourne Stars this summer proof of that.

In the words of Mooney, she's just someone "who sees the ball and hits it". And when she does, "she hits it clean and long".

Meanwhile Mooney, who was the ICC's women's Twenty20 player of the year in 2017, is just as destructive when in form.

She whacked 102 off just 55 deliveries against the Thunder in Cairns on Saturday, as the Heat waltzed into the finals off the back of four wins in five games.

She also forms part of one of the best opening partnerships at international level, helping Australia to a World T20 crown with Alyssa Healy at the top of the order.

"It's been nice to bat with people like that who are comfortable with their own game and know what they need to do," Mooney said.

"If one goes than the other just feeds the strike."

Australian Associated Press