British and Lions coach Warren Gatland has stressed the need to manage players such as Brian O'Driscoll ahead of next week's first Test against Australia.
Knocks
Wales wing North reported a tight hamstring during the Country XV encounter in Newcastle two days ago, while Tuilagi suffered a shoulder stinger three days previously against Queensland Reds, although he is now training again.
Fly-halves Jonathan Sexton and Owen Farrell, who were not involved two days ago, are back in the match-day 23 for Saturday's game against the Waratahs.
And Gatland also parades what could be viewed as his potential Test pack of Mako Vunipola, Tom Youngs, Adam Jones, Alun-Wyn Jones, Paul O'Connell, Tom Croft, Sam Warburton and Jamie Heaslip.
"We don't want to pick up any more knocks or injuries. A few players are coming back, which is good," Gatland added.
"We've got almost a full complement of forwards, which is great, but the backs have tended to take most of the punishment, probably because of the way we have been playing.
"We have been moving the ball a lot and playing a heck of a lot of rugby, and some of the metreage that some of our backs have covered and the amount of work they've done, it has taken its toll a little bit."
Gatland stressed that Gloucester back Twelvetrees would be covering midfield and can expect to start against the Brumbies in Canberra.
"We know he (Twelvetrees) can play 10 as well, and he can goal-kick, but it was specifically that we felt we had a lack of midfield cover," Gatland said.
"And when we looked at it and went through the side there was the potential that, for next week, there could have been three or four players that could have been going into their fifth game in a row.
"We've got to make sure we keep a number of those players fresh for the first Test.
"I was impressed with the Waratahs against the Force (last weekend). Their breakdown is excellent, they are a really good outfit.
"They are missing a few players, but to go to Perth and win that game would have given them a huge amount of confidence.
"They had a poor start to the season by their own admission, but they look as though they are getting better as the season has gone along."
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