Lions duo in fitness race for England
Scrum-half Phillips is battling to overcome an ankle ligament problem that meant he missed Wales's entire autumn series, which concluded with a 33-12 drubbing by Australia.
The February 6 Twickenham clash appears too soon in his recovery process, while Wales boss Warren Gatland can only hope for good news surrounding Rees.
The Scarlets hooker was stretchered off during the first half against Australia after suffering a suspected torn groin muscle.
He left the Millennium Stadium changing rooms with crutches in hand.
Wing Shane Williams also faced a scan following his fifth-minute exit due to hamstring trouble, while a third first-half casualty — Leigh Halfpenny — received a dead leg.
There was precious little cheer to emerge for Gatland during the Wallabies debacle.
But one highlight was provided by 21-year-old Blues flanker Sam Warburton, whose quality 30-minute display off the bench confirmed his status as heir-apparent to Martyn Williams after the 2011 World Cup.
Warburton was only drafted into the match-day 22 on Friday when Wales captain Ryan Jones pulled out because of a back injury, but he showcased his ability, despite Australia's dominance.
"The coaches want the subs to make an impact, to go flat out and play 30 minutes of the hardest rugby in your life," said Warburton.
"It was the hardest 30 minutes I've played. It is totally different playing at this level — the pace and physicality of it.
"I didn't expect it to be such a step up, to be honest.
"It has made me realise that I have to go back and train even harder."
As for the game, Warburton added: "We can't use the excuse that we had players missing.
"It has given us a kick up the backside, and we have to work even harder come the Six Nations.
"We were pretty optimistic we could have done a job on Australia, but in fairness, they were really good. The coaches had a couple of things to say afterwards — in a nutshell, we have to work harder than we have done and we have to raise the intensity again."
Warburton's fellow 21-year-old, Scarlets centre Jonathan Davies, also had his moments, and they are clearly two young prospects with bright international futures.
Davies said: "I've loved every minute of the past five weeks. This has put a bit of a dampener on it, but I was so glad I was involved in the squad.
"International rugby is a lot quicker — you don't have as much time as you do in the Magners League or Heineken Cup — and the dominance Australia had was huge.
"Their physicality in the contact area was far superior, and it was a harsh lesson for us."
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