Defender Christopher Jullien has been ruled out of Celtic's Europa League qualifier against Riga with a back problem.
Boss Neil Lennon revealed the Frenchman has not made the journey for Thursday's clash in Latvia.
Jullien is "struggling" with the issue following Saturday's 3-2 home Premiership win over Livingston.
But his absence is the only further problem for the manager as the rest of his squad emerged unscathed from the weekend victory.
Lennon said: "We’ve only left Chris Jullien behind because he’s still struggling with his back.
"The rest of the squad that was available at the weekend have travelled."
Celtic are strong favourites to prevail in the Latvian capital but Lennon has prepared his players for a "very difficult" encounter.
Riga defeated Copenhagen at home in last year's Europa League qualifiers but eventually went out on aggregate.
The Danes dumped later Lennon's side out at the last 32 and he insists they can take nothing for granted in a one-legged shoot-out.
He added: "They’ll be a tough team to break down. In Kule Mbombo they have a very physical, strong centre-forward. They have good discipline in their shape and, obviously, we’re away from home in Europe so we know that brings its own difficulties.
"They had a great result against Copenhagen last year where they won 1-0 and they lost the tie over two games. This is going to be a very difficult game for us so we’re under no illusions about that.
"The players are well prepared for it. We’re away from home against relatively unknown opponents. We’re trying to prepare them as best we can and they’re well aware of what’s ahead of them."
