PSG stormed to a 5-2 victory in the French capital last week and now The Blues have to do the impossible in West London if they want to reach the Quarter Final.
Chelsea enter the game on the back of their third loss in five games across all competitions following Saturday's 1-0 Premier League defeat to Newcastle United.
Reece James is out
The news does not get any better for Rosenior either as he confirmed that Reece James will miss the clash through injury.
“Reece, he's felt something in his hamstring at the end of the Newcastle game. We don't know the full extent of the injury, but he will be out for tomorrow's game. It could be (serious). With a hamstring injury, it's never great.
“Hopefully we can get him scanned and find out the full extent. Malo (Gusto) is ill today, so we'll look at that tomorrow. With Filip (Jörgensen), he's felt something in his groin, and we will get him scanned.”
A comeback for Chelsea?
As Rosenior deals with the absence of James, he was next asked about attempting to overturn their first-leg deficit where his side must be perfect to progress to the next round.
"If you look at the game in isolation and the scoreline, we were punished by very good players for our own mistakes.
"We have been undone in games by those moments. We can't make mistakes tomorrow.
"We have to remember PSG are European champions for a reason but we know we can compete."
Finally, Rosenior opened up on PSG having the weekend off as they enter the clash more refreshed than Chelsea who will still be reeling from their loss to The Magpies.
"They have more rest, that's normal. I can't speak about other league's schedules and what they do.
"I can make sure my team are ready in terms of the intensity that we need. Hopefully we can turn the tie around. It's difficult but not impossible."