In a few hours, we will know exactly how Gatland's choices have played out - and I wouldn't be surprised if a lot of people only see this after then, on account of having better things to do with their hangover. So arguably, I'm post this simply so I can pontificate on how right I was afterwards - assuming I'm right to begin with.
Of course, most of Gatland's changes weren't particularly optional. Losing Corbisiero and O'Connell will have been a massive blow, for all the quality of their replacements. Parling is a serious operator, and I'm delighted he's getting this chance as he has earned it with club and country these last couple of seasons. I would go so far as to say technically, I see little difference between their games, with Parling ahead as a carrier and O'Connell ahead at the breakdown. But in terms of big game experience and manic aggression there is no Lions forward like O'Connell and anyone would want him in their team for a day like today. As for Corbs, it's a massive shame he keeps breaking so often, because if he didn't he might be recognised as one of the pre-eminent looseheads in world rugby. Vunipola is a hugely powerful man with wonderful hands, and he has blossomed on this tour in a way everyone but Joe Marler will appreciate, but he lacks Corbisiero's experience and technical ability.
In the back division, Bowe for Cuthbert is an optional call, but I regard it as reversing a non-option call to begin with. Its clear how much the Lions coaches rate Bowe and while Cuthbert is a very talented finisher in good form, he lacks Bowe's nous, experience and all round game. Every mistake today could be fatal and even slightly rusty, most people would back Bowe to make less than Cuthbert.
Either way, these calls are unlikely, with the exception of Corbisiero's loss as a scrummager, unlikely to affect the game too much. The interesting calls, the ones that may well make or break this second test, are Dan Lydiate and Ben Youngs.
Youngs has not been in great form, and Gatland has previously stuck with Philips through thick and thin. For all that Mike Philips had a truly awful game last week, it is still a surprise to see this change made, particularly as Youngs hasn't made the strongest case for himself this tour. Lydiate of course is a Gatland favourite, so he is less of a surprise, but his inclusion ahead of Croft and O'Brien does ask some interesting questions. The lineout has been problematic all tour and while it ran smoothly in the first test, that does guarantee a repeat. The Wallabies will have done their homework and with the number of truly outstanding lineout targets cut in half, they might be fancying a cut at Tom Youngs' throwing. If you are happy with the lineout though, which Gatland is, then it might seem more obvious to replace Croft if so minded with O'Brien. Go forwards ball, really denting the golden defensive line, was something of a concern. Sean O'Brien is the single most imposing carrier in the squad. His omission, on face value, seems odd.
Having given the matter some thought, and borrowing a few ideas from elsewhere, it seems to me that Lydiate and Youngs was a call made in tandem with the idea their attributes combined would change the Lions gameplan in both attack and defence.
In attack, it looks like Gatland is hoping to solve breaking the Australian gainline by quicker ball. Croft was very industrious and put in a useful day at the breakdown, but he does not excel at rucking. Lydiate, however, does a lot of it. Remember too that O'Connell's absence must be compensated for here (while I expect Parling to carry a lot). If Lydiate can free up the ball a bit quicker, then Youngs is certainly capable - for all his stepping and meerkatting - of delivering quick ball. More than either of his fellow scrum-halfs, Youngs loves to put tempo on a game. He's less prone to running up blind allies too - just about - largely because he's more likely to get mugged. If Sexton can be provided with a greater supply of quick ball, which these selections might manage, then he can fashion line breaks.
In defence, these selections appear to have been made with one thing in mind, and that is to stifle Will Genia as much as possible. McGeechan said he expected Lydiate's selection was with that in mind, while Ben Youngs' biggest advantage over both Murray and Philips is pace. He can keep up with Genia where they can't. Lydiate and Warburton will look to close off any hope of Genia sniping - Youngs will be lurking to catch him if they fail. For all the danger of Australia's outside backs, if Genia is shackled, there is only so much they can do. Some will continue to ask why not O'Brien, who is no stranger to the noble traditional art of bullying scrum-halves. For that, I point to his penalty count - and not just on tour, but throughout his entire career. Gatland wants reliability here and as such, Lydiate is his man.
These are not the strategies of a man expecting it to be over by half time, and neither is the bench. The Lions should expect less from their set-piece and are short of carriers in the pack to wreak great carnage. But the Lions can wear them down, particularly with a good supply of quick ball. O'Brien and Croft is a horrible thing to spring on anyone from the bench when gaps start to open up. I think Gatland reckons he has late points there.
In a few hours, we will know.
