Bath - Dean Mumm will captain an Australia side to face minnows Uruguay in their second Pool A match on Sunday sporting 14 changes from the starting XV for the opening win against Fiji.
The 31-year-old lock - known as 'Mummy' to his team-mates - had to rush to London shortly after the announcement for the birth of his second child, a son.
"He's going to start learning about the 'benefits' of no sleep, isn't he, because he will be playing off the back of no sleep," said Australia coach Michael Cheika.
"But I'm sure he's got a lot of good feelings at the moment and I'm sure that good feeling will flow through for the rest of his life.
"In the short term, also, I'm sure it will be very good for him."
Cheika has packed the side with experience despite the massive revamp as he seeks to give the whole 31-man squad a run out before crucial games against Wales and England.
Cheika has had the perfect opportunity to work out his first choice XV for those games with the 28-13 win over Fiji last Wednesday and now Uruguay.
"We really want the entire squad to get a touch of the ball early at this Rugby World Cup and get everyone into match mode," said Cheika.
"We will need all 31 players ready for action throughout the tournament and this is the first chance to do that for many of this team.
"We've had a solid preparation for this match considering that we've had to play two games in five days and we're very happy with where the players are at.
"It's important we continue to improve each day as a collective," added Cheika, who has turned the Wallabies fortunes round since assuming control last October culminating in a terrific win over the All Blacks to win the Rugby Championship in August.
Among those to get a start is wing Drew Mitchell, who will win his 66th cap, along with Toulon teammate Matt Giteau a beneficiary of Australia's decision to let in talent playing abroad.
Mumm, whose decision to return to Australia from England this year paid off with his selection for the World Cup, replaces hooker Stephen Moore as skipper. Moore will be on the bench and in line to come on for his 98th appearance.
"It's an incredible honour to lead this group of players," said Mumm, who leads a side with a total of over 800 caps.
"Stephen Moore, Michael Hooper and Adam Ashley-Cooper have done an outstanding job as a leadership team this season and I'm extremely grateful to have the opportunity to contribute to what they've created and lead the team on Sunday," added Mumm, who made his debut back in 2008.
"This is a really important match in our campaign and four players are getting the opportunity to play in their first Rugby World Cup match, so it is a significant occasion for those players and a chance for us to build on the performance against Fiji."
Teams:
Australia:
15 Kurtley Beale, 14 Joe Tomane, 13 Henry Speight, 12 Matt Toomua, 11 Drew Mitchell, 10 Quade Cooper, 9 Nick Phipps, 8 Wycliff Palu, 7 Sean McMahon, 6 Ben McCalman, 5 Will Skelton, 4 Dean Mumm (c), 3 Toby Smith, 2 Tatafu Polota-Nau, 1 Scott Sio
Substitutes: 16 Stephen Moore, 17 Sekope Kepu, 18 Greg Holmes, 19 Kane Douglas, 20 Rob Simmons, 21 Will Genia, 22 Bernard Foley, 23 Tevita Kuridrani
Uruguay:
15 Gaston Mieres, 14 Leandro Leivas, 13 Joaquin Prada, 12 Andres Vilaseca, 11 Rodrigo Silva, 10 Felipe Berchesi, 9 Agustin Ormaechea, 8 Juan Manuel Gaminara, 7 Matias Beer, 6 Juan De Freitas, 5 Franco Lamanna, 4 Santiago Vilaseca (captain), 3 Mario Sagario, 2 German Kessler, 1 Mateo Sanguinetti
Substitutes: 16 Nicolas Klappenbach, 17 Oscar Duran, 18 Carlos Arboleya, 19 Alejandro Nieto, 20 Diego Magno, 21 Fernando Bascou, 22 Alejo Duran, 23 Alberto Roman