Simeone's men enter the top-of-the-table La Liga clash second to Barca only on goal difference and five points clear of third-placed city rivals Real Madrid.
The former Atletico defensive midfielder accepts Gerardo Martino has better players at his disposal but urged his team to focus on what they could achieve as a group.
"Tomorrow's game is a different game for the players in term of the motivation they usually have," Simeone said.
"We accept the reality, they have better players but we are committed to the team. In that game we feel strong. That's one of the possibilities that bring us to compete tomorrow."
Just like Martino, Simeone played down the significance of the result, with both insisting it would not be decisive.
"We are talking about a very important league game but it remains a league match, not a final," Simeone said.
"They have a great squad, with large variations. We try to play our game and improve with what we've got."
Simeone urged his team to continue focusing on one game at a time, despite potential title talk almost midway through the league season.
"It depends on us more than ever and we must reinforce this thought. The argument we have is that we keep alive going game by game," he said.
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