"There are one or two players that are a little bit sore who next week may be out of contention because they won't have been fit early enough in the week. That's potentially what might happen," said Gatland.
"By the time Saturday comes around they might all be fit, but it is possible one or two will be ruled out because they aren't fit enough early in the week. Brian could play on Saturday, but if he plays on Saturday and gets another knock that would rule him out of contention for the Test.
"He is 34 now and we've spoken about managing him - he has been great so far on tour and there is no reason to play him this weekend. I spoke to both Brian and Paul O'Connell before the tour and said that we would be smart about how we looked after them so they were fit for the big matches."
So far, so good on that score this tour and both men are intent on filling in the one gaping hole in their otherwise exemplary careers by winning a Test series with the Lions. At the other end of the age and experience scale, however, Manu Tuilagi and George North are seeking success at a much earlier stage.
Tuilagi missed the midweek win over the Combined Country XV and is ruled out for the game against the Waratahs because of the shoulder 'stinger' he picked up against the Queensland Reds. He hopes to be in the mix again for Tuesday night's clash with the Brumbies.
North left the field at half-time in Newcastle during the week complaining of a tight hamstring and the young Welshman is not being risked in Sydney.
"Manu's shoulder has been improving all the time and he was training today and the medics are happier with him. George had a tight hamstring from the other night. He is being treated and we hope he is potentially going to be in contention for next week," said Gatland.
"We have a few bodies that have been knocked around in the backs and that's why Billy Twelvetrees has been brought in. As we go from one tour to the next you start to realise how tough it is.
"Even from four years ago there has been a step up in physicality and players being able to handle two games per week. It's tough and it is something we need to be mindful of at the end of the tour - do future squads need to be a bit bigger because of the step up in physicality?"