Fabio Quartararo was left baffled as to why his leather race suit split open as he slipped from pole position to a fourth-place finish at the Catalan Grand Prix.

MotoGP championship leader Quartararo was aiming to seal back-to-back wins in Barcelona following his triumph on the circuit in 2020, but the Monster Energy Yahama driver slipped up early on and failed to finish on the podium.

Miguel Oliveira got Red Bull KTM's first win of the season, and the third race victory of his career, with Johann Zarco and Jack Miller completing the top three.

Quartararo was second until the final three laps, when Zarco made a daring overtake and caught the Frenchman out.

To complicate matters, Quartararo's suit had opened, with the 22-year-old's chest protector also slipping out.

He cut two corners as he battled with Miller for third, and was handed a three second penalty which cost him a third straight podium position at the Catalan Grand Prix.

"What happened I don’t know, I just know that I had the leathers completely open," he explained to reporters.

"I tried to just put it in a normal position again, I couldn't do it. So was difficult to ride, but unfortunately, it happens.

"It happened today, so Alpinestars is looking at how it's possible because at the end of the race it was possible to close it again.

"But it's like this, it was not our day but I can be happy with this fourth position… well, third, but finishing fourth."

Whether or not it was @FabioQ20 taking his zipper down on purpose, I believe that should have been a black flag. At this level you can’t be allowed to race at 350km + with your leathers open.
— Casey Stoner (@Official_CS27) June 6, 2021

Former MotoGP champion Casey Stoner tweeted his thoughts on the incident, insisting Quartararo should have been disqualified from the race.

"Well, I think I already have a penalty that I don't agree [with], demoted three seconds from P3 to P4," Quartararo said when Stoner's comments were put to him.

"I think this penalty is quite enough. It's finished, the race is finished, everything is safe.

"So, I think right now it's not enough to talk anymore because the race is finished. I think there's no point to talk anymore about these possible things."

It was a race which belonged to Oliveira, with the Portuguese rider holding the lead for 23 laps.

"The most difficult thing about the race was the mental ability to stay calm, it was so easy to be aggressive or to just override the tires at the beginning," he said in a news conference.

"I felt like that was the key, stay calm and the race will come to me."

Elsewhere in a frantic race, six-time MotoGP champion Marc Marquez crashed out on Turn 10, which also claimed Valentino Rossi and Aleix Espargaro.

Marquez has now failed to finish the last three races, a career first for the 28-year-old.