Atletico Madrid's Portugal forward Joao Felix is likely to miss thos weekend's derby clash at Real Madrid after being diagnosed with a muscle injury on Wednesday. The 126 million euros ($139.78 million) club-record signing suffered the problem in Sunday's 0-0 draw with Leganes and did not train ahead of Saturday's match at the Santiago Bernabeu. "Given the ongoing pain after a rest day, the club's medical services performed tests to diagnose the injury," Atletico said in a statement, without saying how long he would be sidelined. The 20-year-old Felix has struggled to make an impact with Atletico as Diego Simeone's side languish fifth in La Liga, 10 points adrift of leaders Real Madrid after 21 games. (For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)