Marcelo is aware the pressure is on and he fears it would increase if sixth-placed Sevilla go in front.
He said: "Playing Sevilla is always a very tough match and I don't think this time is any different.
"They have some very good players. Also, they want to get a place in Europe and we have to make it difficult for them.
"We have to get ahead. We cannot wait for the opponent to score and then chase a result.
"It would be much better to get in front. We have to go there and win. While there is still a mathematical chance of us winning the title, we will work hard."