Atletico Madrid star striker Diego Costa faces a fitness race ahead of Tuesday night's Champions League meeting at Barcelona.

The in-form frontman, who has registered seven goals in just five games in this season’s competition, was forced to pull out of a training session at the Nou Camp on Monday night with a knee injury.

Initial reports varied over the severity of the problem, with coach Diego Simeone telling Spanish television that he will be evaluated over the course of the day.

Earlier, Simeone exuded calm confidence as he looked ahead to the encounter.

The perception of Atletico has changed from underdogs to serious contenders over the last few months, and Simeone summed up the determination within his camp as he said: “I am sure we will compete. It’s going to be a great tie.”

In the wake of widespread tributes to his contribution at Atletico since being appointed just over two years ago, Simeone predictably played down his personal importance in favour of espousing the group-first ethic that characterises his team, whilst emphasising they are not a force to be taken lightly.

“I know we have an identity of play, and it is the historical identity of Atletico. We are continuing the history that has characterised the club. We’ve got a group of marvellous players.”

Simeone has no illusions about the task facing his side as they attempt to oust Barca over two legs, and he takes little comfort from the fact that all three of this season’s previous meetings between the teams resulted in tight draws.

“This will be the hardest game,” he said. “In the first, we were at home, and in the third, Messi was recovering from injury. It will be very difficult and they will want to finish the tie in the first leg.”