Captain Morgan, an inspirational leader in the Foxes' remarkable Premier League title success last season, has not played for a month due to a back injury and will not be rushed back for the weekend meeting at Selhurst Park.
But, with relegation all but staved off following Craig Shakespeare's appointment as manager until the end of the season, overcoming a 1-0 deficit to Diego Simeone's Atletico in their last-eight tie is now the priority.
Shakespeare told a news conference: "Wes trained on Thursday but not with the squad. He's 50/50 for Atletico but won't feature against Palace.
"We'll only put him in if he's ready. There'll be a conversation with Wes and the medical staff but we won't take a gamble.
"He's captain and sometimes you lead by example and sometimes you have a quiet word in an individual's ear. He does that really well."
With Morgan's fellow central defender Robert Huth suspended for the Atletico clash, Shakespeare may take the chance to shake things up against Palace with Daniel Amartey under consideration for a defensive berth.
Shakespeare added: "If I think it's a benefit [he could play there]. Players are adaptable and some can play multiple positions and Daniel's one of those.
"But I need to assess them all. We had a light session on Thursday and I need to see what the injury situation is. We need to be competitive, we still need the points."
CS: “Wes Morgan trained yesterday, but not fully with the squad. He won’t play against Palace and is 50/50 for Atletico Madrid.” #CryLei— Leicester City (@LCFC) April 14, 2017
Palace will present a stiff challenge with their own bid to escape relegation boosted by a 3-0 thrashing of Arsenal on Monday.
And Shakespeare is well aware of the threat posed by a side led by Sam Allardyce, under whom he worked as part of the England set-up last year.
"Their upturn in form doesn't surprise me," said Shakespeare. "Having seen Sam work at close quarters I know how diligently he looks at the opposition.
"With the individual ability of their wingers, Wilfried Zaha and Andros Townsend, our full-backs will have to work hard to keep them quiet."