The Europa League champions have won only once in La Liga since the start of the year, losing three and drawing one, and have slipped to seventh, 11 points behind fourth-placed Valencia after 21 matches.
The club's demanding fans have been voicing loud discontent but midfielder Juanfran, who joined from Osasuna in the January transfer window, insists Atletico have what it takes to upset Barca and kickstart a positive run of results.
"We had several very bad weeks with bad results and the dressing room is pretty upset," he told a news conference on Wednesday.
"But I have found a strong group here, as there is nobody who is not trying to get the team out of this," he added.
"The team is surely going to play much better from here until the end of the season and we are going for our goal of making it into the Champions League. Obviously the atmosphere will improve if we win on Saturday."
Juanfran said the key to the match against what he called "the best team in the world" would likely be getting after the Barca players and not letting them settle into a rhythm.
"We are going to go for them from the opening minute and make sure they do not feel comfortable," he said.
"It is not going to be easy, but we will also have our chances, although 90 minutes feel very long at the Nou Camp.
"To win, we have to run more than them and be as effective as possible. Those are the team's ideas. We are going to Barcelona to win."
FATAL BLOW
Barca moved seven points clear of great rivals Real Madrid thanks to last weekend's 3-0 win at Hercules, which matched the La Liga record of 15 straight wins set by Real in the 1960-61 season.
Jose Mourinho's expensively-assembled Real side crashed to a shock 1-0 defeat at Osasuna, two weeks after a frustrating draw at Almeria.
They host Real Sociedad on Sunday knowing that another slip-up could deal a fatal blow to their hopes of ending Barca's two-year reign as Spanish champions.
Third-placed Villarreal, who are six points behind Real, are at home to struggling Levante, while Valencia, a further four back in fourth, host Hercules on Monday.
