A dramatic late winner by Celtic substitute Shunsuke Nakamura gave the visitors a 1-0 win and all three points in their SPL clash with St Mirren at Love Street.
Hoops keeper Artur Boruc had made two fine saves, from David van Zanten's volley and Billy Mehmet's drive, to keep the home side at bay and the game seemed to be heading for a draw.
But with four minutes remaining, Nakamura, on for Barry Robson just after the hour mark, curled home a free-kick from 25 yards to claim all three points.
St Mirren were incensed by a foul being given against Mason on Nakamura which allowed the Japanese midfielder to show his set-piece expertise.
And although they fought for an equaliser, it was beyond them.