Barcelona coach Xavi Hernandez said it would be a huge disappointment if his side were to be knocked out of the Champions League group stage for the second consecutive season this week.
However, a win would draw Barca level on points with Inter, with both sides still to face Bayern and Plzen. The head-to-head record between the two sides, followed by overall goal difference, will separate the teams if they finish level after six games.
"It would be a massive disappointment not go through, but we are only thinking positively," Xavi said in a news conference on Tuesday.
"It's become complicated for us, but we will attack and be brave and go for the three points to stay alive in the competition. Only three points is enough."
Barca have just three points from three games in Europe so far this season after back-to-back defeats to Bayern Munich and Inter.
"The situation is uncomfortable," Xavi added. "We missed too many chances in Munich and there was the refereeing controversy in Milan, as well as not attacking well there, but Wednesday gives us an opportunity to fix that."
"We have the talent and there is also a desire for revenge for what happened in Milan," Xavi said. "I hope that anger serves for us to play better and attack better.
"We were indignant after that game, which is normal, but that's it now. Now it is about playing better. If we improve, maybe we won't have to speak about referees. The reality is we are not at the level of a few weeks ago and we have to play better."
Barca followed up defeat to Inter with a 1-0 win over Celta Vigo on Sunday to remain top of LaLiga and unbeaten domestically, but striker Robert Lewandowski is now without a goal in two games for the first time since he joined the club.
Xavi says Barca must strive to involve Lewandowski, who has 12 goals in 11 appearances this season, to keep their Champions League hopes alive.
"We have to improve, we have to link with him more," Xavi said. "In the last two games, we have not found him enough. In Munich, we created but missed too many chances. In Milan, it was more difficult up against three big centre-backs.
"We have to play closer to Robert. He was an island in the last two games, especially in the first half in Milan. We have to be closer to him for the good of the team and for Robert."
Barca remain without Jules Kounde, Ronald Araujo, Andreas Christensen, Hector Bellerin and Franck Kessie for Inter's visit. Memphis Depay is also likely to miss out but, along with Kounde, could return for Sunday's game against Real Madrid.