The game has been spoiled by the blustery wind swirling round the stadium but Celtic have coped with the conditions far better than Rangers.
Celtic also had a perfectly good goal chalked off when Hartson had the ball in the net on 14 minutes, the linesman flagged for offside bu TV replays clearly showed that Hartson was at least a yard onside when the pass from Larsson was made.
It was Larsson who set Petrov up with a fantastic pass through the middle that left the Bulgarian one on one with the keeper and the midfielder ran on to slip the ball past Klos.
HT Rangers 0 Celtic 1