World Cup 2018: Scotland duo Scott Brown and Stuart Armstrong ruled out through injury
Scott Brown and Stuart Armstrong have been ruled out of Scotland's crucial upcoming World Cup qualifying double-header through injury.
Celtic manager Brendan Rodgers said they are sidelined with hamstring and calf injuries, respectively.
Scotland face Slovakia and Slovenia next Thursday and Sunday as they seek to secure a play-off place.
"It's unfortunate for both players, unfortunate for us, and obviously for Scotland," Rodgers told BBC Scotland.
"We don't think it's overly-serious. It's something that's probably a few weeks. It puts them out of the game tomorrow and the international games."
Gordon Strachan's side are currently fourth in Group F, six points behind group leaders England.
The Scots host Slovakia at Hampden on 5 October before travelling to Slovenia three days later.
Victories over Malta and Lithuania have raised hopes Scotland can beat their Group F rivals to claim a play-off place.
The Scots made a poor start to their campaign with only four points gathered in their first four group matches.
However, 10 points from the subsequent four games mean they will finish second behind leaders England should they win their next two.