Celtic skipper Scott Brown faces three months out of action with a nasty hamstring injury.
The 29-year-old was injured during Sunday's 1-1 friendly draw with Rapid Vienna and tests carried out in Austria revealed he almost tore the hamstring off the bone.
The best-case scenario would see Brown miss just eight weeks of action but that would still rule him out of this month's Champions League second-round qualifier with KR Reykjavik.
He will also sit out potential third-round and play-off ties should the Scottish champions progress that far.
But Parkhead boss Ronny Deila admits Brown could be sidelined for as long as three months - ruling him out of the opening two group games.
Brown's injury is also a major blow for Scotland boss Gordon Strachan.
His captain will definitely miss the Dark Blues' opening Euro 2016 qualifier against World Cup finalists Germany on September 7 and faces a race to get fit for clashes with Georgia and Poland the month after.
Deila said: "It's bad news for Scott. He will be out for two months, maybe three. The hamstring has been almost ripped off.
"He doesn't need an operation, which is a positive thing. But it is quite a big injury.
"It's hard for him and it's hard for us. But we can't do anything about it. We have to try to get him back on the pitch as quick as possible - but we have good midfielders who can step up.”