Coach Brendan Rodgers has confirmed that Casper Schmychel will be involved in a recovery from a hamstring injury in the next five to six weeks.
The 38-year-old, who played 46 appearances this season, scored the first goal in the quarter-finals of the Denmark Nations League last month.
The Danish captain, who has 81 cups, played in a 5-2 defeat, which meant the Portuguese 5-3 to advance.
Asked about the possibility of a lack of five to six weeks, Rodgers told Celtic TV: “This is the only thing that, day by day.
“Casper tend to think that it may not be, but it will certainly not be available in the near future.