The two teams know each other extremely well and Harmanpreet admitted India enjoy testing themselves against Australia and always lift their game when taking on the six-time T20 World Cup champions.
"They (Australia) are one of our favourite opposition and hopefully our best will come on that day (Sunday)," Harmanpreet added.
"We know that these tournaments when every game is must win and sometimes when things that doesn't go your way, you have to at this point, you have to, give your best.
"And I think that game is very important.
And if we win that, I think we will definitely get a lot of confidence from that."
It will be just shy of eight months to the day of India's victory over Australia at the 50-over World Cup when the two teams meet in London on Sunday, with the two rivals having also met in a three-game T20I series Down Under at the start of this year that Harmanpreet's side won 2-1.
The two teams know each other extremely well and Harmanpreet admitted India enjoy testing themselves against Australia and always lift their game when taking on the six-time T20 World Cup champions.
"They (Australia) are one of our favourite opposition and hopefully our best will come on that day (Sunday)," Harmanpreet added.
"We know that these tournaments when every game is must win and sometimes when things that doesn't go your way, you have to at this point, you have to, give your best.
"And I think that game is very important. And if we win that, I think we will definitely get a lot of confidence from that."
