Khedira sidelined for Barca clash
The German international picked up the adductor problem in his right leg in last week's King's Cup final victory over Barca and missed Real's La Liga game at Valencia on Saturday.
Khedira's place in the starting lineup for the nine-times winners will likely be taken by France international Lassana Diarra. Long-term injury victim Fernando Gago also misses out, while centre-back Ricardo Carvalho is suspended.
The return leg is on May 3 at the Nou Camp and the successful team will play English Premier League leaders Manchester United or Bundesliga side Schalke 04 in the final at London's Wembley stadium on May 28.