Veteran batsman Shaun Marsh believes his younger brother Mitch has found his happy place, while Glenn Maxwell is certain the in-form allrounder will have a "massive" Twenty20 World Cup.

Mitch Marsh has been in hot form in the T20 international arena since July, posting four half-centuries and two other scores in the 40s since then.

He also posted a brilliant century for WA earlier this month in a domestic one-day win over South Australia.

Marsh, who is expected to have first crack at the all-important No.3 spot in the batting order, now looms as a key ingredient in Australia's hopes of winning the T20 World Cup for the first time.

"Mitch Marsh is going to have a massive tournament. I don't think I've seen anyone hit the ball better - ever," Maxwell said.

"We all gathered around his nets and just watched him hit the ball - it's been pretty extraordinary.

"I'd be really surprised if he didn't have a good tournament ... he's flying."

Shaun believes it is happiness off the field that has helped Mitch the most.

"He's found a real balance in life away from cricket," Shaun said.

"He got engaged recently. He's in a really happy place away from cricket and I've got no doubt that's helped him be a bit more relaxed and enjoy the game.

"I know how talented he is. It's nice to see that coming out of him now and I can't wait to see him bat over there.

"We speak regularly. We're brothers, but we're really good friends as well."

Shaun feels batting at first drop is what will best suit Mitch at the World Cup.

"He's going great. He's full of confidence and he's played so well over the last six months," Marsh said.

"It's the best I've seen him hit the ball in a long time.

"His confidence is up and he's feeling loved, and I'm sure he's going to do a really good job over there."