Great mates Justin Langer and Matthew Hayden, who forged one of cricket's best opening partnerships, will become enemies in the lead-up to the sudden-death clash between Australia and Pakistan.

Langer has led Australia since 2018, while the years of pain Hayden caused Pakistan during his playing days have been quickly forgotten after making an immediate impact as the country's batting coach.

The former destructive left-hander joined Pakistan's coaching staff in September

Pakistan have been the dominant team of the tournament, finally beating nemesis India in a World Cup match en route to a likely undefeated group stage.

They are heavily favoured to take care of minnows Scotland in their final pool match on Monday (AEDT).

Langer cracked a huge smile when asked what the upcoming match-up with his long-time friend would mean.

They opened the batting together in 113 Test innings, smashing 5655 runs at an average 51.88 during a golden era of Australian cricket.

"We've been back and forth messaging throughout the tournament," Langer said.

"He's (Hayden) really enjoying (coaching Pakistan's batters).

"No insights though, we've been keeping business to business.

"It's going to be good to see him because I haven't seen him for a long time.

"There's lots of relationships in cricket, but when it comes to Thursday night, we'll put our friendships down for three hours and we'll get down to business so it should be good fun."

Langer's Australians will enter the match buoyed by a standout finish to the group stage.

They quickly put the disappointment of a thrashing to England behind them, securing big wins against Bangladesh and West Indies.

Veteran opener David Warner has made a welcome return to form, smashing an unbeaten 89 - the highest score by an Australian at a T20 World Cup - in the eight-wicket victory over the West Indies.

"He's literally elite fit," Langer said of the 35-year-old.

"He's always fit, but he's at a different level at the moment and that tells me ... you don't just flick a switch and become fit, you've got to work very hard at his age.

"You saw the way he played, ran between the wickets in hot conditions, and that's a great tribute to his professionalism and how hungry he is to keep playing great cricket."

Australian Associated Press