Wallabies' Alaalatoa shares toll of tour as he looks to win back starting role

Having kissed goodbye his own newborn baby daughter to go on the Wallabies tour, prop Allan Alaalatoa can empathise with star winger Marika Koroibete's shock decision to stay home.

In a blow to Australia's hopes as they take on Japan, Scotland, England and Wales over the next five weeks, workhorse Koroibete opted to remain with his Melbourne-based family, who welcomed a third son in July.

The Wallabies open their tour against the Brave Blossoms at Oita's indoor stadium on Saturday.

Koroibete missed his son's birth while playing for Australia against France in July and with the blessing of the Wallabies this time chose to put family first.

Linking with Japan's Panasonic Wild Knights next season on a lucrative multi-year contract, it's uncertain when - or if - the 2019 John Eales Medallist will play for the Wallabies again.

Jordan Petaia, who replaced Koroibete in the last Rugby Championship win over Argentina, or Tom Wright, are set to start against Japan.

Alaalatoa shared Koroibete's pain and said it was heart-breaking to leave his daughter, Niah, who was born late last month.

"Jumping on a plane on Wednesday was probably one of the hardest (things)," the Brumbies captain said.

"Being with our newborn daughter for two weeks was definitely really special and it was sad to know that you will probably be away for five to six weeks.

"But that flicks into a sense of motivation and making sure that I make the most of this opportunity while I'm away from my family."

Alaalatoa left the Wallabies camp after their first Rugby Championship win over South Africa and now must work to reclaim his starting tighthead jersey from tackle-busting Taniela Tupou.

"I was sitting back at home and watching Nela (Tupou) probably play some of his best footy and guys like Tom Robinson coming off the bench and performing as well," he said.

"It's great for the Wallabies to have that competition and for me coming back into the squad, I've got to make sure that I earn the right to play and to wear the jersey again."

Alaalatoa said he saw plenty of growth in the pack in his absence as they adjust to demands of Wallabies forwards coach and Brumbies boss Dan McKellar.

"Our set piece has definitely grown ... I think Dan's involvement has really helped," the 28-year-old said.

"I know that a lot of the boys in the squad respect him and what he has to say so I think definitely there's been a huge improvement around our set piece."

The last time the Wallabies were in Japan they made a disappointing quarter-final exit from the 2019 Rugby World Cup.

With a new coach in Dave Rennie and a large change in personnel, Alaalatoa said they were only focused "on the now".

"Our focus is on us getting better and how we can improve from our last game," he said.