Ryan Jones has withdrawn from the Wales side to take on Australia in the Invesco Perpetual Series climax at the Millennium Stadium on Saturday (Kick-off 5.30pm).
Gethin Jenkins will captain the team and Jones is replaced at No8 by Andy Powell, who moves across the back row, with Dragons flanker Dan Lydiate promoted from the bench to the blindside to win his second cap.
Lydiate's place as a replacement is taken up by Sam Warburton, who faces the prospect of tackling the Wallabies for the second time in a week after representing the Cardiff Blues against their midweek touring side on Tuesday.
"Ryan pulled up in Tuesday's conditioning session with a back problem," said Wales physio Mark Davies.
"This obviously needed time to settle and unfortunately the problem has not resolved in time for him to be available on Saturday.
"He has been receiving treatment and was unable to train yesterday, but today we have taken the decision that he is simply not going to be ready to take the field."
Sam WARBURTON (CARDIFF BLUES - Cap No 1,070)
DoB: 05.10.88. 1.88m / 6'2". 15st 9lbs / 99kgs
International record: 2 caps (W 2)
The Webb Ellis Cup visited Lampeter on Monday to recognise the fact that the town is celebrating a major milestone as it is believed the first ever game of rugby played in Wales, was in fact played in Lampeter 150 years ago.
Cardiff Blues U18 Girls will go into Sunday's Gemau Cymru with an extra spring in their step after Welsh internationals Elinor Snowsill and Philippa Tuttiett offered some last minute tips at a training session earlier this week.
Rob Howley and Josh Lewsey addressed more than 250 community club coaches and referees at the first WRU National Community Conference on the weekend. The volunteers benefitted from coaching masterclasses and workshops in a bid to connect all levels of the rugby pathway in Wales.
UEFA has today confirmed the Football Association of Wales (FAW) has been successful in its bid for the Millennium Stadium to host the 2017 UEFA Champions League Final on Saturday 3rd June, 2017 (kick-off: 19.45hrs GMT).
The winners of a filmmaking competition organised by the education charity Into Film and the WRU enjoyed a behind the scenes tour of the Millennium Stadium - and a chance to be photographed with the WRU's fire-breathing, rugby loving mascot, Scorch The Dragon, and Welsh international, Jake Ball.