Atletico Madrid right-back Juanfran Torres is a major doubt for the Champions League semifinals with a bruised hamstring muscle, while left-back Filipe Luis is set to play on despite breaking a finger in the 1-1 draw with Leicester on Tuesday.
Juanfran limped off early in the second half of the quarterfinal second leg at the King Power Stadium, which saw Atletico progress 2-1 on aggregate, with Filipe Luis soon following after picking up a hand injury, with both players undergoing tests in Madrid on Wednesday.
Reports in Spain say Juanfran's injury is likely to keep him out past the semifinal first leg date of May 2 or 3, though Simeone has been boosted by his other specialist right-back Sime Vrsaljko returning to training following a knee problem.
"Juanfran Torres has undergone medical tests this evening in Majadahonda," a club statement read. "After the MRI test, the right-back suffers 'a grade II muscle injury with an associated bruise in the quadriceps of the right thigh.' Our player will undergo physical therapy and rehabilitation treatment."
In better news for Atletico, Filipe Luis will be able to play while his broken finger heals and is set to feature in Saturday's La Liga game at in-form Espanyol.
"Filipe Luis has undergone medical tests this Wednesday in Majadahonda's Fremap clinic," another club statement read. "X-rays have confirmed that the Brazilian left-back suffers 'a fracture of the IV metacarpal bone of the right hand.' The Brazilian international will be able to train and play with a splint that will protect his hand."
Atletico will face either rivals Real Madrid, Juventus or Monaco in the last four, with the draw being made on Friday.
Atletico striker Fernando Torres said whoever they get, they are "ready to suffer" to make a third final in four years.
"There is no preferred opponent, whoever we get will be tough. Our experience has taught us that," Torres said. "We must be humble against any team. At this stage you will have to suffer, and we are ready to suffer and beat anyone."
Torres, 33, is out of contract at the end of the current campaign, with there being no firm indication yet that a new deal is forthcoming.
He said he hoped to still be at the club next year, though such thoughts were being parked while the team headed into the decisive part of the season.
"Everyone knows my wish -- the same as when I came back, and same as it will always be," he said. "I cannot hide what I feel for the club and what I want to do in the future. But at the moment it is an absolutely secondary issue. We have in front of us what could be the most special and most important season in the club's history. We cannot focus on anything else."