Unleaded fuel drops back below £1 per litre, and is the lowest price for years.
Asda and Morrisons have both cut the cost of their petrol to under £1 a litre - bringing "Christmas cheer" to motorists.
The Asda price drop - falling by two pence to 99.7p - will last three days at all of its 277 filling stations from Friday. While Morrisons said they hope to keep their price of 99.9p for "as long as possible".
Asda said the price of diesel will also be cut to 103.7p per litre, while Morrisons will cut theirs by 1p.
The cut comes days after the RAC told motorists to expect a price fall before Christmas.
RAC Fuel Watch spokesman Simon Williams said while the drop would bring "Christmas cheer to many", he wanted to see the low price being held longer than three days.