Cheika's comments came just after the affable Australian announced that Ireland prop Cian Healy would undergo a late fitness test to see if he can play his part in the competition's showpiece event.
"Cian has had a bit of an illness over the last seven to 10 days," said Cheika, having named the 22-year-old as an either or alongside Mike Ross on the Leinster bench.
"He got back into training yesterday so we'll just wait and se how he shapes up before we make a decision on whether he can take his place in the 22.
"He's just been a bit sick. He's had a stomach virus and he's lost a bit of weight. He's been recovering but, in that position, it's important that you're weight's right and you're feeling good.
"He trained yesterday, we'll monitor him again and we'll then decide whether he'll take his place in the 22.
"CJ (van der Linde) is in the best form he's been in for a while now," added Cheika, in reference to the giant South African who comes into the starting line up for Healy, with Cook Islander Stan Wright moving to loosehead.
"He's come through a few games, is feeling good and has got himself sorted out. I think he's really looking forward to tomorrow's fixture."
Much has been made of the abilities of the two top sides in the league when it comes to throwing the ball around and scoring tries out wide.
And with players of the calibre of Rob Kearney, Lee Byrne, Godon D'Arcy and Tommy Bowe involved, that focus is hardly surprising.
But while those players may win the plaudits come Saturday night, Cheika has told his forward pack, and in particular his tight five, that victory rests largely on their shoulders.
"We're coming up against one of the best packs around," explained Cheika.
"I think the tight five understand that they're going to be attacked heavily by the Ospreys tomorrow. That's where the game's going to be won or lost.
"There haven't been a lot of words said but there's a knowing feeling around that group of players that they're going to have to put in a massive shift.
"I've got a feeling it'll be a bit closer to the single digit numbers where the game's going to be decided," Cheika replied when asked about the match up between British & Irish Lions full backs Kearney and Byrne.
"Those guys will then influence the scoring. It's the platform that's got to be laid by every player with the physicality that's involved in the game, from Rob Kearny at 15 all the way to Stan Wright at No1 and all the subs.
"It will be the player who wants to take responsibility to come and make the difference, and that may well be Kearney because he's been doing it very well since the Six Nations. Since he's come back, he's been one of our best backline players."
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