The pair join former Olympic fencer Evelyn Halls in the key roles, completing the leadership team of Chef de Mission Ian Chesterman.

Additionally, New South Wales Institute of Sport chief executive Kevin Thompson has been appointed by the Australian Olympic Committee (AOC) as head of performance.

"Each of these Olympians has special qualities to contribute to the team environment and each will bring their own experience and perspective," President John Coates said. 

"They will prove a very important resource for Ian." 

Chesterman claimed the latest appointments show the AOC is putting the athletes first for next year's Olympic Games. 

"We are focused on giving our athletes the very best opportunity to perform at their best," he said.  

"Our three Deputies totally understand the environment of Olympic competition and will be a great support to our athletes and coaches in the team.

"It is very exciting to have such a high-calibre group together. 

"Each brings something different but each has a fantastic work ethic and great empathy for what’s important to athletes."

Winner of eight Olympic medals, including two gold, former Susie O’Neill admitted she was looking forward to returning to the Games. 

"I’m hoping that I can provide that reassurance to the younger athletes," said the 45-year-old, Australia's Chef de Mission at the 2014 Summer Youth Olympic Games in Nanjing. 

"When they see that I am just an everyday person, they can believe in themselves and that anything is possible."

The 33-year-old Brennan, winner of the Olympic gold medal in the rowing single sculls at Rio 2016, claimed the prospect of contributing to the team so soon after retirement was exciting.

"Every Olympian wants to keep contributing in one way or another," said Brennan, who carried Australia's flag during the Closing Ceremony of Rio 2016. 

"We have that bond. 

"To be stepping into this role gives me the chance to make a different type of contribution."

Halls, who represented Australia at Athens 2004, will be continuing her administrative career at Tokyo 2020. 

"Undertaking the role of Chef de Mission for our Youth Olympic team in Buenos Aires last year gave me a great appreciation of the difference you can make for our young athletes," she said.

"To see that young team meld as a unit and really perform to their best was very satisfying."

Thompson previously worked at the English Institute of Sport, during which time he directed the North East and North West Institutes of Sport which supported athletes who won 20 of the Olympic 47 medals for Britain at Beijing 2008, including the highly-successful British cycling programme.

"Leading a team to deliver HQ performance support services whilst working closely with Dr David Hughes and his medical team is a great opportunity," he said. 

"I look forward to the challenge of the Games and working through the requirements of each sport to support them in optimising athlete performances."

Australia will be hoping to arrest a decline in performances since Sydney 2000 when they won a record 58 medals, including 16 gold.

Their total number of medals has declined at every subsequent Games.

At Rio 2016 they won 29 medals, their lowest total since Barcelona 1992.