Chelsea midfielder Frank Lampard says they must hold their nerve against PSG tonight.
To reach the Champions League semis, Chelsea will need to overcome a 3-1 deficit.
Emotions are sure to be running high at Stamford Bridge but Lampard says it is crucial his side do not get caught up in the occasion.
He told London Evening Standard: "It certainly is our biggest game of the season. To be 3-1 down in a Champions League quarter-final means it's a huge match for us.
"We want to go through, we want to win the Champions League as everyone else does. We are aware of the situation. It's a massive challenge and we will approach it that way. The decisive thing will be using the talent we have and keeping our discipline on the night. We can't go with crazy heads just because we need to get back in the game. We have the ability and, hopefully, the talent will come through.
"A fast start is very important. It's not about getting carried away but we need to show that urgency and attack in a fast way. Closing them down fast, moving the ball fast, if we can do that and play to our game, we can give ourselves a chance. We're playing against a top?level team. It's going to be difficult whatever way you look at it. We will try to give ourselves the best opportunity by performing to our highest level."