Scotland all-rounder Michael Leask sees no reason why his side cannot score a surprise upset over Australia to secure their T20 World Cup progression on Saturday.

Group B remains wide open heading into the final day of pool action when England face Namibia before Scotland will know what result is required when they meet Australia later in the day.

Scotland are two points clear of England, though Jos Buttler's side have a superior net run-rate after hammering Oman in a complete thrashing on Thursday to keep their Super 8s hopes alive.

England will be expected to overcome Namibia earlier in the day, leaving it likely Scotland must overcome already-qualified Australia to seal their group-stage progression.

Although Scotland have lost all five white-ball meetings with Australia, each coming in the 50-over format, Leask believes his team should be confident heading into the game.

"Australia are one of the best in the world," Leask said.

"It is going to be a tough game, but why can't we go and do what we've done before and cause an upset?"

Scotland are in this position after their washout against England before a commanding victory over Namibia, while Buttler's side are trailing due to their defeat to Australia.

An unlikely scenario still brings the chance for Scotland to lose by a narrow margin and progress even if England beat Namibia, and Leask says this situation was always on the cards.

"We knew coming into this game it would be," he said. "England had two tough games to play and they've played the first one very well.

"We always knew this was going to be a must-win game for us and it's a hell of an opportunity for us to go and play really good cricket and take on one of the best in the world."

Josh Hazlewood mooted the idea that Australia may concede the game in a certain manner to send England out, though team-mate Pat Cummins believes a decision like that is not plausible.

Regardless, Leask insists Scotland are firing on all cylinders before this decider.

"Our boys are firing, we've got some good skill sets, some nice spinners, some good seamers and then batters who are playing really well," Leask said.

"We're going at this game quietly confident. Our batters are probably going to have to step up knowing we're facing the best in the world.

"They've probably got the best all-round bowling attack in the world. It's going to have to be two or three batters in that batting innings that are really going to have to put Australia under the pump with a ball.

"We know that it's capable of happening and that's possible."