Formula One's governing body introduced an extra practice session ahead of a potentially title-deciding Saturday sprint and said Sunday's Qatar Grand Prix could become a mandatory three-stop race after Pirelli raised tyre safety concerns.
The FIA said a 10-minute session would be held before the sprint shootout that decides the grid for the 100km race to allow drivers to adjust to track changes, with revisions to the track limits at turns 12 and 13.
The shootout will start 20 minutes later than scheduled at 1320 GMT, with the 19-lap sprint then going ahead as planned at 1730 GMT.
Red Bull's Max Verstappen is poised to win his third championship in the sprint, the Red Bull driver needing to score only three points to put the title out of reach of team mate Sergio Perez.
Verstappen has already qualified on pole for Sunday's grand prix.
Further tyre analysis will be carried out after the sprint to decide if further action is needed before Sunday's main event.
Should that be the case, a directive will be issued ordering teams not to exceed 20 laps on new tyres used in the race.
"This number would rise to 22 for any used tyres fitted in the race, to account for in-out laps in qualifying," it added.
"All drivers will be obliged to perform at least three tyre-change pitstops during the race."
Pirelli's analysis of tyres used in Friday's practice found a separation in the sidewall between the topping compound and the carcass cords on many of those used for around 20 laps.
"It is the view of the FIA and Pirelli that a significant number of additional laps on these tyres could result in circumferential damage of the tyres with subsequent air loss," added the governing body.
"Tyres analysed with lower lap numbers showed a much-reduced extent of the issue."
The FIA said the issue had likely been caused by the tyre sidewall coming into contact with the 50mm "pyramid" kerbs used at the circuit, with drivers riding the kerbs to get the quickest lap time.
