Neil Lennon is not sure if Derk Boerrigter will be available to face Elfsborg in midweek after injury ended his Celtic debut early.
The Dutch winger, signed only in midweek, came off near the end of the first-half of the 2-1 win over Ross County that marked the start of the defence of their Scottish title.
He suffered an ankle injury in an accidental clash and Lennon admitted he had no idea if he would be fit in time to play in the second-leg of their Champions League third qualifying round tie on Wednesday, when they try to defend a 1-0 lead in Sweden.
"You can see what Derk brings to the team, that pace and balance on the left," Lennon said.
"He was coming in off the line well when James Forrest was down the right hand side.
"He looked a real threat in the first half but we have a bit of a sweat on for Wednesday night to see how he is.
"He jarred his ankle. It was a total accident, he clipped Mihael Kovacevic's Achilles and it has twisted. So we will have to see how he is."