The Argentine forward has not featured in La Liga since November but the Atletico boss fully expects the Rojiblancos to have to face him this weekend
The Argentine has been out of action in La Liga since his injury in early November but, after a goalscoring return in the Copa del Rey in midweek, the Rojiblancos coach suspects that Gerardo Martino will start with the attacker this weekend.
"As a fellow Argentine, I am extremely happy that Messi is back at his best," Simeone told reporters at the pre-match press conference.
"We need to win the World Cup and he is a decisive player who can help us to do it. I really hope that he can play his best football during these next few months.
"Will we see a Barca without Messi tomorrow? I don’t think so. They have a lot of variations to their game but I can’t see him not taking part in tomorrow’s match."
Atletico have been extremely impressive - domestically and in the Champions League - this season and Simeone hopes that his second-placed Liga side can replicate the draws they battled for in the Supercopa earlier in the 2013-14 season.
"It’s not a final. It’s only a league game," he added. "Now it’s our turn to face them. It’s a very, very important game but still just a league game like any other.
"We will be attempting to play our own game and utilise our weapons. We want to put in a similar performance to the one we put in against them in the Supercopa.
"Right now, we are in a very privileged position in the table and staying there depends on us alone."
If either the Blaugrana or the Rojiblancos win at the Calderon this weekend, the victor will go top of La Liga outright by three points.