“I think it’s going to be difficult for him to play.” Those were the ominous words uttered by Diego Simeone on Monday to TVE, referring to a player who embodies the mentality that Atletico Madrid’s coach has inspired in his squad to turn the club from laughing stock to La Liga leaders and Champions League quarterfinalists. 

Diego Costa also represents Atletico’s best chance of further upsetting the balance of power and knocking out mighty Barcelona to reach Europe’s last four. But his place on the Camp Nou pitch on Tuesday evening is now in grave doubt.

The man with 25 goals to his name this season, seven in the Champions League, lasted just 10 minutes on the famous turf in Barcelona on Monday before leaving Atletico’s training session and heading down the tunnel with the club’s physio. Having scored both goals in Atletico’s win at Athletic Bilbao on Saturday, Costa was withdrawn with a groin injury. Still, with the problem initially not thought to be serious, it remains to be seen whether there is some kidology going on from Simeone or whether his star player is unable to feature in what its arguably Atletico’s biggest match in 18 years.

His brace in ensuring Atletico remained a point ahead of Barcelona in La Liga in what was their toughest fixture before the two contenders meet on the final day demonstrated just how important Costa is to Simeone’s side. A line of suitors from Europe’s elite reportedly prepared to pay up to €50 million to secure his services this summer is further evidence of his standing. Like his team, Costa’s technical quality should not be overlooked but his and their ability to punch above their weight is about much more than skill.

Costa is a defender’s nightmare; never giving up a lost cause, prepared to battle for the ball with every inch of his body, on occasion by illegal as well as legal means. And Atletico are just the same. Not so long ago a team that appeared to revel in finding new ways to fail, they are now a side that no outfit relishes meeting. And they particularly relish going up against the big teams.

Barcelona know this all too well. In three games against Los Colchoneros this season Barcelona have yet to win. Led by the steel of Miranda and Diego Godin and flanked by the ever consistent duo of Juanfran and Filipe Luis, Atletico have one of Europe’s best defenses. Protection is provided by the energy and tenacity of Mario Suarez and Gabi in the center of midfield. Those six provide a superb base.

While Atletico now have more capacity to control games with the ability on the ball of Koke and the underrated creativity of Arda Turan, Atletico are still at their best when able to play on the counter attack. And with Costa taking far more chances than not, that is what makes them so dangerous against Barcelona. Atletico will be looking to keep things tight but also with a keen eye on getting an away goal. Such a strike at the Camp Nou could be priceless in a quarterfinal tie that is arguably the closest of the four to call.

Not so long ago there may have even been just cause to make Atletico Madrid favorites to progress. It is just over three weeks since Barcelona fell to their third defeat in six league matches. And the 1-0 reversal to Real Valladolid was the worst of the bunch, with the Catalans offering up an insipid display perhaps worse than any the club has produced since Pep Guardiola made them Europe’s dominant club.

But since then Barcelona have won five matches in a row and look better than at any other time during Tata Martino’s difficult reign. Previously ponderous going forward there is now a real coherency and pace about the side in attacking areas. Key to that, of course, has been Lionel Messi getting back to his best. Although three have been penalties, his nine goals in his last five appearances are testament to the Argentine’s rejuvenated threat on the opposition goal.

Barcelona have looked at their best against Manchester City and Real Madrid when Martino has played Andres Iniesta as one of the front three to provide the side with better balance. Yet, still, as they showed both in the second leg against City and notably in a frenetic Clasico, Barcelona now lack the ability to control the game as they once did. Xavi remains brilliant but no long dictates the play as he once did. It contributes to Martino’s side being more vulnerable to quick-paced attacks, as Real Sociedad also notably showed in their recent win.

Atletico will certainly not allow the first leg at the Camp Nou to be as open a spectacle as did their Madrid neighbors, but if Costa is fit then then they will retain the ability to punish Barcelona on the break. The tie looks likely to remain on a knife-edge heading back to what will be a cauldron-like atmosphere at the Vicente Calderon in a week’s time.

Prediction: Barcelona 1-1 Atletico Madrid