Atlético Madrid forward Diego Costa risks missing their Europa League semi-final games against Arsenal after he was diagnosed with a hamstring injury on Friday.
The first legs will be played on April 26, with the second legs on May 3.
Atletico are bidding to reach their third European final in four years having been runners-up in the Champions League in 2013-14 and 2015-16.
Diego Simeone's Atletico side, second in La Liga, have already faced English opposition this season in Europe, losing 2-1 at home to Chelsea and drawing away as they bowed out of the Champions League at the group stage.
It precedes the UEFA Champions League draw, which starts at 13:00 CET.Who is in the draw?
He added: "We live with the reality and that is the Europa League". With what they have, they tend to do very well in knock-out competitions.
In previous rounds the Spanish side have run to comfortable victories, often finishing the tie by the first leg with hefty victories.
Marseille will host underdog Salzburg in the first leg of the other semifinal.