United face a quarter final second leg in the Europa League against the Spanish side, and are 2-0 up from the away leg in Spain.
Rashford has been struggling with an ankle problem for the past few weeks, and did not train on Wednesday.
The attacker has been limited to 60-70 minute appearances for United recently, and missed England's World Cup Qualifiers during the most recent international break.
"I'll have to give him as much time as possible - his foot is still a little bit sore, but fingers crossed," said Solskjaer.
And Solskjaer was still frustrated about the cautions shown in Spain.
"It's never a positive thing to not have every player available but we've got players ready to deputise and come into the team of course," the Norwegian added.
"It was a booking amnesty after this quarter-final so we hoped to get them through, but there were some easy yellow cards that the ref handed out.
"We're ready to deal with that."