There was no shortage of drama during Friday's action for the Sao Paulo Grand Prix, with World Championship rivals Lewis Hamilton and Max Verstappen at the heart of proceedings.
On paper, it seemed like a routine day at the track for the two men battling it out for the 2021 F1 World Championship.
Hamilton finished qualifying with the fastest time ahead of Verstappen, setting the stage for a tense Sprint Qualifying race that would feature the two on the front row of the grid.
The results took on even greater importance with word that Hamilton would serve a five-place grid penalty - after fitting a new Internal Combustion Engine (ICE), his fifth of the season - regardless of where he finishes on Saturday.
However, that was only the beginning of what proved to be a day full of drama.
Questions surrounding Hamilton's DRS
It all began when Hamilton was referred to the stewards over a possible Drag Reduction System (DRS) infringement following qualifying.
Although the seven-time World Champion finished with the fastest time, issues arose when FIA F1 Technical Delegate Jo Bauer checked Hamilton's W12 car.
"The uppermost rear wing element adjustable positions were checked on car number 44 for compliance with Article 3.6.3 of the 2021 Formula One Technical Regulations," read a statement sent out by the FIA.
"The requirement for the minimum distance was fulfilled. But the requirement for the maximum of 85mm, when the DRS system is deployed and tested in accordance with TD/011-19, [was] not fulfilled.
"I am referring this matter to the stewards for their consideration."
A breach of the technical regulations would see Hamilton excluded from the qualifying results. It would also force him to start the Sprint Qualifying race from the back of the grid, or potentially the pit lane, a disastrous development given that he already trails Verstappen by 19 points in the Driver's standings.
Hamilton situation unresolved
The news meant that Mercedes were formally summoned before the stewards at 19:15 local time in Brazil over the alleged breach.
The hours passed, but no ruling was handed down. Finally, news filtered out from the FIA shortly before 22:00 local time that a ruling wouldn't be made on Friday.
"The stewards have adjourned the hearing relating to Document 18 of the 2021 FIA Formula 1 Sao Paulo Grand Prix as they await further evidence that will not be available until the morning," read a statement.
In the meantime, Hamilton's rear wing has been impounded.
Verstappen summon adds intrigue
Although Hamilton's alleged DRS breach was adjourned until Saturday, there was still time for one last surprise, this time involving World Championship leader Verstappen.
Fan video emerged following qualifying, which showed Verstappen looking at and appearing to touch Hamilton's rear wing.
Parc ferme conditions begin at the start of qualifying, and given that the Sao Paulo Grand Prix is a Sprint Qualifying weekend, it means they commence a day earlier than usual.
Parc ferme rules are clearly defined in Article 2.5.1 of the International Sporting Code, which state: "Inside the parc ferme, only the officials assigned may enter. No operation, checking, tuning or repair is allowed unless authorised by the same officials or by the applicable regulations."
As a result, Verstappen and a team representative have been summoned by the stewards at 09:30 local time on Saturday.
What will happen now?
It remains to be seen what penalties, if any, will be handed out to Hamilton and Verstappen.
However, there is the genuine prospect of Friday's top two qualifiers dropping from the front to the back of the grid, which would add yet another twist to the tale in an already enthralling 2021 campaign.
The F1 paddock will be waiting for news with bated breath...
Video: The secrets of the Interlagos Circuit
Follow Rudy van Buren as he takes you on a flying lap around the Interlagos Circuit, home of the F1 Brazilian Grand Prix.