Chelsea vs. PSG: Rosenior admits Blues 'must be perfect' to have any chance of upsetting European champions

Liam Rosenior has acknowledged that Chelsea will need to deliver a "perfect" performance against Paris Saint-Germain on Tuesday night.

The Blues are trailing 5-2 on aggregate ahead of welcoming the defending champions to Stamford Bridge for the second leg of their Champions League last-16 tie.

Only four teams in the history of the competition have progressed after losing the first leg by a margin of three goals or greater.

Chelsea's hopes of joining that illustrious list has been hampered by a potentially-serious injury to one of their key players.

Speaking at a press conference on Monday, Rosenior has acknowledged two areas where his team can ill-afford any mistakes.

Rosenior admits need for Chelsea improvement

Rosenior has admitted that his players must find a way to keep their concentration for an entire match, both in the short and long term.

He told reporters: "If you look at the game in isolation, you look at the scoreline, we were punished by some very good players by our mistakes.

"I think it's been a theme. I think we have performed consistently very well, but we've been undone in games by moments of focus or concentration.

"For us to go through tomorrow, we need to be perfect in terms of not making mistakes, in terms of our performance in possession.

"We have to remember that PSG are the European champions for a reason, but we've also shown in times that we can definitely compete and beat them in isolated games."

Rosenior concedes PSG rest is advantage

PSG benefitted from having their Ligue 1 fixture with Nantes rescheduled from the weekend, a request granted by officials from France's top flight.

Rosenior admits that it is an advantage for PSG, saying: "Obviously, they have more rest. That's natural. That's normal.

"I can't speak about other league schedules or what they do. What I can do is try and make sure that my team and our team are ready to give absolutely everything into this game in terms of the intensity, in terms of the quality that we need.

"Hopefully, we can turn around a difficult scoreline, but not an impossible one."

Nine of the 10 outfield players from Parc des Princes remained in the team for Saturday's Premier League fixture against Newcastle United, many of whom looked fatigued during the closing stages of the match.