Blues captain John Terry admitted the team's form had suffered recently.
He told Sky Sports: "We haven't been performing as well as we'd have liked, but we had a great team spirit tonight. Maybe we had lost it a bit, it's been difficult.
"We've had to pick ourselves up and look to move forward.
"We hope it's the kick start we need after we've had a few iffy performances."
The Blues won by the same scoreline at the Mestalla in last year's quarter-final and Terry believes Wednesday's victory was better.
"I think it was," he said. "We fought back and came right back into the game.
"We had many great performances and needed a collective performance tonight."
The Chelsea captain also insisted he had had no side-effects of wearing the protective mask on his face.
"No problems at all, I just had to get used to it in training," he said. "It felt quite comfortable, I just wanted to get out there."