Jones and his players have received a barrage of criticism since their 40-6 loss to Wales last weekend left Australia's hopes of reaching the knockout stages hanging by a very thin thread.
The Wallabies are relying on Fiji losing at least one of their remaining pool matches but will also need to run in four tries against Portugal in Saint Etienne to secure a bonus point.
Jones was in typically combative form as he announced his team for the match on Friday, again apologising for the results but insisting that the young World Cup squad he selected had been the best available.
"If people are going to have a problem with the results, they come to me, right?" Jones told reporters at the team hotel.
"And if they need a fall guy for the World Cup then it's obviously me. When you become a head coach of a team, you take on that responsibility."
Jones dropped the centre pairing of Samu Kerevi and Jordan Petaia after they struggled to make an impact in the losses to Fiji and Wales, with young guns Izaia Perese and Lalakai Foketi coming into midfield.
"Samu has just been a little bit off his best," Jones added.
"Jordan had a slight calf injury, which is OK now but he couldn't train. So we just decided to give those two guys the opportunity and we think they'll play well against the Portuguese team."
Fraser McReight will return at openside flanker with Tom Hooper moving back to the blindside as Jones opts for a more mobile back row after going for power against the Welsh.
"It's going to be a work-rate game," he said. "Portugal play a side-to-side game and I feel that having two workers there will suit us best."
James Slipper again starts at tighthead prop in his 21st World Cup match, surpassing former scrumhalf George Gregan's record for appearances at the showpiece tournament.
Jones conceded that his press conference appearances were acting as a lightning rod to protect his young squad, who had endured a torrid few days since the Wales defeat.
His hope was that the humiliation of last week's drubbing in Lyon would drive the young Wallabies to greater heights in the future.
"Every team I've seen develop has a game like that, that is etched in the memory but actually acts as a spur for them to work a little bit harder and understand what it takes to win at this level," he said.
