The Monaco Grand Prix's mandatory two-pitstop rule will be used again in 2026, despite the controversy triggered by its introduction at this year's race.
In a bid to add excitement to the event around the streets of Monte Carlo, F1 added a race-specific demand that forced drivers to stop twice for tyres.
The idea was that mandating an extra pitstop would add more uncertainty at a venue where overtaking is very difficult, and hopefully prevent the race from being too processional.
The move triggered huge controversy, however, as a number of teams adopted unusual tactics in getting their drivers to work together in holding up rivals to help open up gaps in the traffic for their team-mates to drop into.
Racing Bulls, Williams and Mercedes all used their second cars to open up space for their lead cars to effectively get a free pitstop - before then swapping cars and repeating the process.
Williams driver Carlos Sainz - who described the tactic as "race manipulation" - said that if the two-stop plan was to remain in place then something needed to change.
"It's something I definitely didn't enjoy doing," he said at the time. "Something definitely the sport should look into.
"Ultimately you're driving two or three seconds off the pace that the car can do. You are ultimately manipulating the race and manipulating the outcome a bit.
"We should find a way that this cannot be done in the future because I have the feeling every year people are going to do it more and more, and it's [already] become more of a trend in the last years."
He added: "I fear that as we move forward, teams are going to be more comfortable doing what we did and it's going to become too much."
The controversy prompted calls from several teams to think carefully about whether the two-stop idea should be repeated, and it did not appear in the original 2026 F1 sporting regulations.
However, following an e-vote approval this week by the World Motor Sport Council of changes to the 2026 rules, the two-stop requirement has now been added in.
Article 6.3.6 states that: "For the race in Monaco, each driver must use at least three sets of tyres of any specification...during the race."
The return of the two-stop will likely prompt teams and F1 bosses to try to think up ways to prevent the kind of manipulation that overshadowed the 2025 race.
This will be especially important because, with the tactic having been executed so well by Racing Bull and Williams in particular, it will likely become an obvious route for a team at the front to try to win the race in 2026 if they end up with both cars near each other on the grid.
Mercedes driver George Russell, who got so frustrated at being held up by the Williams drivers that he cut the chicane at one point to overtake Alex Albon, said that the attraction of playing these games at Monaco was that it was so easy to block other cars.
"Driving four seconds off the pace here is dead easy," he said. "Our strategist said anything less than three seconds pace advantage is a 0% chance of an overtake. You need 4.5 seconds for a 50% chance of an overtake.
"So you could effectively put an F2 car out there and they've got a chance of holding up an F1 car."
