Celtic defender Stephen McManus was knocked out unconscious in a clash with Rangers striker Daniel Cousin in yesterday's 3-0 defeat.

The Celtic captain was carried off on a stretcher near the end of the first half, after a clash of heads with the Rangers striker, and was treated by medics.

He was later brought around but Strachan admits the situation was concerning at the interval.

"That was a problem at half-time, when he was in the dressing room and we were worried about Stephen, really concerned," Gordon Strachan told Setanta.

"The fact is that he's regained consciousness, so I was going to pop in and see him, but it's a waste of time just now because he'll be having a lot of tests at the moment."

McManus now seems set to miss Wednesday's Champions League clash with Benfica.

Strachan added: "We keep our fingers crossed that Stephen's going to be fine."

McManus, 25, is also a key man for the Scotland team, whose next match is the crucial Euro 2008 qualifier against Italy on November 17.

Scotland manager Alex McLeish said: "I certainly hope that he's fit for the national team next month."