Wales have been hit by a late injury blow ahead of Saturday's clash with Australia after Ian Evans failed a fitness test on a knee problem.
Evans had been due to start at lock in place of Bradley Davies, who was left with concussion after being struck by Andrew Hore in the first minute of the defeat to New Zealand last weekend.
The Ospreys forward had complained of pain in his knee during training this week, and he will not be risked against the Wallabies at the Millennium Stadium.
Cardiff Blues second-rower Lou Reed has been called into Warren Gatland's starting XV as Wales look to sign off a wretched November series with a morale-boosting victory.
A statement issued by the Welsh Rugby Union read: "Evans has been excluded in order to give him optimum opportunity to manage his injury.
"While he completed training this week, he has not been totally free of pain and after extended discussions between the WRU and his regional medical team, it has been decided to withdraw him from the game in order to seek further investigation and opinion."
Gatland had already made three changes among the forwards, with Gethin Jenkins replacing Bath's Paul James at loosehead and Scott Andrews coming in at tighthead for the injured Aaron Jarvis.
The one form change comes in the back row, where Aaron Shingler replaces former captain Ryan Jones, who drops to the bench alongside uncapped prop Samson Lee.
An Australia victory would condemn Wales to the third tier of countries for next Monday's draw for the 2015 World Cup.
Wales (revised): 15 Leigh Halfpenny, 14 Alex Cuthbert, 13 Jonathan Davies, 12 Jamie Roberts, 11 Liam Williams, 10 Rhys Priestland, 9 Mike Phillips, 8 Toby Faletau, 7 Sam Warburton (c), 6 Aaron Shingler, 5 Luke Charteris, 4 Lou Reed, 3 Scott Andrews, 2 Matthew Rees, 1 Gethin Jenkins.
Replacements: 16 Ken Owens, 17 Ryan Bevington, 18 Samson Lee, 19 Ryan Jones, 20 Justin Tipuric, 21 Tavis Knoyle, 22 Dan Biggar, 23 Scott Williams.