Drivers face a weekend of travel disruption as a crucial stretch of the M25 shuts for major roadworks.
National Highways has closed the motorway in both directions between junctions 10 and 11 to build a new bridge. The closure, which began at 9pm Friday, will last until 6am Monday.
The AA has sounded the alarm, warning that diversion routes could be "incredibly busy" as traffic is forced off the motorway.
Motorists are urged to steer clear of the M25's west side altogether. Those who must brave the chaos are advised to bin their satnavs and stick to official diversion routes.
This will be the third of five weekend closures of the M25 - which encircles London - as part of a £317m project to improve Junction 10 in Surrey.
The project, due to be completed in summer 2025, will increase the number of lanes at Junction 10, which is one of the UK's busiest and most dangerous motorway junctions.
The works clash with Goodwood Festival of Speed, Wireless Festival, Wimbledon finals weekend and the final of Euro 2024 on Sunday.
Also impacted could be holidaymarkers travelling to Heathrow and Gatwick airports.
Chris Wood, of the AA, said: "With many football fans changing their plans following England's victory over Holland, it's likely to be incredibly busy in and around London.
"We advise drivers to plan their journey accordingly, avoiding the west side of the M25 if possible, and to check ferry and tunnel operators' websites for updates before setting off.
"Prepare your vehicle by checking oil and coolant levels, tyres and make sure you have enough fuel or electric charge to cover the planned diversions."
National Highways has thanked drivers for largely sticking to the official diversion route in the previous closures and has urged motorists to do the same this weekend.
The diversion route follows the A3, A245 and A320.
Senior project manager Jonathan Wade said: "The previous two closures have gone well, with significant progress being made during both.
"We would urge all drivers to follow the official diversion route as this is the best chance of reaching your destination in good time.
"Please ignore your satnavs and follow our diversion route instead."
The final two weekend closures as part of the project will take place later this year.
