Simeone, however, praised Costa as he told reporters: "Diego Costa always give us physical and moral strength.
"He is a very important player for the character he transmits to the team, and his potential as a football player.
"He didn't play the last days, and we'll see if he is in the first 11 or not. He trained very well [on Monday], and he showed enthusiasm.
"When he is enthusiastic, it makes the fans, his team-mates, and the technical staff happy."
Dortmund and Atletico are the runaway leaders in Group A with two wins from as many matches, while Club Brugge and Monaco are yet to register a point.
"Regarding his football, we are not surprised," Simeone added. "He is a decisive player, close to the area, short moves that make the full-backs find him to finish the game.
"And confidence is something so important for a player. Paco just found continuity and he has answered with something he did in the teams where he has that situation."