I wouldn't be surprised if the Lions backrow is Lydiate, Warburton, Faletau, but if I was a Lions selector, the backrow would be SOB/Croft, Tipuric, and Heaslip.
Tipuric had an immediate impact in the breakdown when he got on against the Reds, where Warburton was decidely very average, but is forgiven for his first game back from injury.
Lydiate, as well, is a shadow of his 2012 form, and was, in my mind, outplayed by Quirk and co.
Also would like to make the point that the Lions are very average at the breakdown; the fact the Reds without Gill still got quick ball far too easily would be a worry for Gatland. No doubt will be a point of difference for the Wallabies is how well we generate quick ball, and stifle the Lions' possession.