Fox sent a header past the Dons goal as the half-time whistle approached Marc Crosas blasted in a long-range effort that sailed wide as the players headed in.
Marc Crosas replaced Cameroon midfielder Landry N'Guemo for Celtic on the brink of half-time in a tactical switch as the lethargic Premier League team looked for a change in fortunes.
The former Manchester City striker took a Crosas pass and drove down the right flank, leaving centre-back Frazer Wright trailing in his wake before cutting in to the box and drilling the ball past Combe.