It had to happen sooner or later, didn't it?
The entente cordiale between Lewis Hamilton and Sebastian Vettel was always going to be tested as their battle for the world championship intensified.
They are after all, as Mercedes boss Toto Wolff said, warriors.
The clash occurred during the final safety car intervention. The leading driver in its wake is entitled to manage the pace.
The safety car was barely 150m in front of Hamilton, and there were concerns from the previous restart that he had come close to overtaking it.
The trick is to be sufficiently far behind it that you can be running at full speed as you reach the safety car line, where former racer Bernd Maylander will pull off the track.
The first check made by driver steward Danny Sullivan, a former F1 racer and the winner of the 1985 Indianapolis 500, was to study Hamilton's telemetry to confirm that he had not brake tested his rival. He had not. He eased the throttle to maintain the correct distance to the safety car, and Vettel ran into him.
Naturally, it was a tense time for both drivers, one preparing to defend down the very long straight that followed, the other keen to slipstream his way into the lead.
Said Wolff : "You are at war the moment that the race starts...
"Sebastian's an emotional guy. He will know that that didn't look great. I don't need to talk to anybody or bang any heads."
Perhaps what we saw was the strain that Vettel is under.
It was a hard weekend for Ferrari, with speculation that part of the reason for their worst qualifying performance of the year vis-a-vis Mercedes may have been due to the tightening of engine regulations - notably the one which precludes the use of some additives in the lubricating oil which can also act as fuel, creating more power.
Vettel was also the driver who most often visited the escape roads in practice, suggesting that Ferrari were for once - instead of Mercedes - struggling to get their tyres in the correct working temperatures.
His behaviour had echoes of his German compatriot Michael Schumacher. Back in 1997, the price of deliberately turning into an overtaking rival at racing speed, even if you ended up going off track yourself, was that you got all your championship points annulled.
Today, the penalty is only 10 seconds of standing still on the naughty step.
While Schumacher acted on his streak of ruthlessness, Vettel's move is more one of petulance.
This wasn't the first time the FIA has been lenient with him. Last year in Mexico, he got away with an apology to race director Charlie Whiting after launching a tirade of abuse from the cockpit.
Like all spoilt brats, Vettel needs somebody in authority to take him to task.
The notion that the penalty for a loose headrest - the reason why Hamilton lost the race - should effectively be worse than the penalty for deliberately driving into another car, filled many people in the paddock in Azerbaijan, and the global audience, with disgust.
Undoubtedly a bit of needle will add to the box office.
Why else are sports as visceral as boxing or cage fighting so popular?
But what had thus far made the contest between two multiple champions so engaging is that they had made this a sporting contest.
"The sport needs the rivalry and I think what we've seen today has the ingredient of a great championship," Wolff suggested. "At a certain stage, the best ones that compete for world championships can't be friends. Maybe we've seen the limitation of the respect today."
