Firefighters are bracing for erratic winds that threaten to undo their progress in controlling the Morwell coalmine fire, where the area on fire has so far been reduced by 85 per cent.

The Country Fire Authority fears 45km/h winds expected after 9am on Wednesday may fan the fire burning on the southern cliff of the Hazelwood open-cut mine and threaten Hazelwood power station.

Incident controller Bob Barry said fire services had called in extra resources, including two strike teams and two water-bombing helicopters as they prepare for the worst.

"We could have a fire run out from the mine like we did last Tuesday," he said.

"I reckon we may slip backwards slightly because the wind we will experience will impact on the batters for sure, but we're in a lot better position today than we were last time."