The tie is evenly poised at 1-1 following the first leg at Stamford Bridge, where Willian was the star of the show as he put the Blues ahead, but Lionel Messi nabbed an all-important away goal for Barca.
"It is important in these kind of games not to lose any players, we have to keep our discipline," Willian told the London Evening Standard.
"The past shows that Chelsea have never lost against Barcelona with 11 men. It is vital we keep all 11 on the pitch until the end of the game.
"We must still play with the same level of intensity as the first leg, no doubt. We have to do a similar game as we did in the first match. We made it difficult for them. I believe we can do the same job against them on their own ground as we did at Stamford Bridge. We will go for it."
So far, Liverpool and Manchester City are the only English clubs to progress into the quarter-finals, as Tottenham Hotspur and Manchester United have failed to do so.