Asda, Morrisons and Sainsbury are all to cut the price of their petrol as oil prices fall.
Sainsbury said it was cutting its fuel prices by 5p a litre for those spending over £50, while Asda and Morrisons are cutting their petrol prices by 3p and 4p respectively.
The move is in response to oil prices falling from a $147 a barrel peak to $130.
Asda trading director, David Miles said: "We are seeing a more stable reduction in oil prices allowing us to pass on the savings to customers.
"We urge other retailers to follow our lead at a time when customers need as much help as possible."
At Asda, the price of petrol and diesel will fall to 113.9p and 128.9p at all its forecourts.
Last week's AA Fuel Price report showed petrol prices rose 1.5p from mid-June to mid-July, compared with 7p rises in the previous month.
It found average petrol prices were at 119.5p a litre and diesel prices were at 133.1p.