Carlos Sainz was looking on course for another Q3 appearance in qualifying for this weekend's Bahrain Grand Prix - right up to the moment when his McLaren went into a spin at the start of his first flying lap of the second round of the session.
Video footage suggested that the right rear wheel had suddenly locked up going into turn 1, but it was initially unclear whether this was the result of a brake issue or a gearbox failure.
The last could have proved costly in terms of grid penalties, so it was with some relief that after conducting an immediate investigation the team was able to confirm it had indeed been a rear brake failure.
"We experienced a problem with the braking system in Q2 which denied him an opportunity to show his true performance," team principal Andreas Seidl stated. "Apologies to Carlos: he’s felt strong in the car all weekend
Not that it was much consolation for Sainz himself, who looked disconsolate as he jumped out of his marooned car under a red flag.
“You obviously get out there at 300kph and you hit the brakes and suddenly the rear brakes locked completely," he told the media when he got back to pit lane.
“I don’t know really what happened," he said. "We obviously hit an issue at the start of Q2, which locked up the rear axle and that was it.
"But I’m very disappointed. I had just got through Q1 with only one set of tyres, I had saved some softs for later in the qualifying.
“But that set of mediums was so important for this weekend, and it looks like it is completely flat-spotted and I’m not going to be able to use it for the race. It looks fairly destroyed, so I’m very disappointed.”
As a result of not setting a time in Q2, Sainz faces starting from 15th on the grid for tomorrows race. That's a setback to McLaren's hopes of fighting for third place in the constructors championship against the likes of Renault, Racing Point and Ferrari.
Asked what he could still achieve in tomorrow's race from so far back, Sainz was downbeat.
“The problem is the strategic options available for us with the tyres we’ve got," he explained. "We’ve been trying to save those harder set of tyres for the race
"At the moment I don’t know what I’m going to have available tomorrow with the problems I’ve had today," he added. "For us to have that problem with the medium tyre flat-spotted, and lose it probably for the race, is the worst possible scenario.
"It leaves us with very few options if we have lost [the set of mediums] with that lock-up, he told Movistar. "That's why I'm very angry. I'm sorry, but I'm very angry.
"You can come back, but it gets very complicated,” he continued. “Especially because the top ten is going to start with the medium, and those of us who start behind them won't have any advantage over them.
“[But] there’s pace in the car, no doubt about that, and I felt really, really at home the whole weekend."
Seidl exonerated Sainz from any responsibility for the incident, stating: "We have to analyse it. I think that the rear axle has locked up and there was nothing that Carlos could do.
“It is disappointing because we had a competitive car today," he acknowledged. "Carlos was in good shape all weekend and it's a shame.
"But that's all there is. Now it's time to analyse what happened in Carlos' car, reset, and start again tomorrow. It will be an interesting race, with many challenges, with two stops or more, and we must try to come back.
"Tough one, but we won’t give up and I’ll give it my all in the race to recover as many positions as possible.”
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