Microsoft doesn't expect the Xbox 360 to have sold more units than its rival consoles in the US during the crucial month of December.

Why? Because the Xbox 360 sold out.

Last night Microsoft community mouthpiece Larry Hryb, aka majornelson, took to Twitter to explain the situation before NPD figures are released this evening.

"I found out we ran out of consoles at end of the month so don't expect to win Dec," he said.

He added: "Jan/Feb supply is tight as well. Likely amazing YOY growth numbers for Xbox."

Microsoft, Sony and Nintendo will all be hoping for strong Christmas sales of their consoles. Both Microsoft and Sony expect motion sensing add-ons Kinect and Move to have buoyed sales, and Nintendo's Wii and DS traditionally sell well in the run up to Christmas.