Lewis Hamilton's bid to win a hat-trick of consecutive titles hangs in the balance after he retired from the Malaysian Grand Prix with yet another engine failure.
Here, Formula One writer Philip Duncan looks at five things we learned from what could prove to be a pivotal race in the championship.
1. Lewis Hamilton doesn't know who to blame right now.
After seeing his dreams of winning a fourth title take a severe dent, Hamilton headed to Kuala Lumpur - a one-hour drive from the Sepang circuit - for dinner. Chicken was the order of the day for the Briton before he boarded Mercedes non-executive chairman Niki Lauda's private plane to Tokyo on Monday morning.
Lauda joked: "I will give him two tequilas and he will certainly be entertained. We will get out of the plane and we will have no more worries."
It's probably a bullish prediction, after Hamilton appeared to hint at foul play within his own ranks. While Hamilton later turned to the idea of a celestial interference - he said "it feels right now that the man above, or a higher power, is intervening" - you cannot help but feel the seeds of doubt have been sown.
2. It was not the weekend Mercedes dreamed of.
Mercedes was poised to equal the longest winning streak in Formula One history, and also to wrap up the constructors' championship - all at a race it regards as a home grand prix, given its title sponsor Petronas is a Malaysian company.
Yet the T-shirts were hastily put back in their box, and a celebratory event scheduled for Kuala Lumpur on Tuesday was shelved. Sunday's race must be considered as one of Mercedes's worst of the year - second only to the calamitous events in Spain, where Hamilton and Nico Rosberg took each other out.
"Lewis claims sabotage" - the headline splashed across the biggest English-language newspaper in Malaysia on Monday morning - is hardly one that will please Petronas chiefs.
3. The stars could be aligning for Nico Rosberg.
Rosberg is 23 points clear of Hamilton with just 125 points to play for. And credit to the German for a fine comeback drive after he was in last place following a collision with Sebastian Vettel. But Rosberg certainly rode his luck, too. He was not at fault for the incident with Vettel, but he was fortunate to continue given the race-ending damage sustained by his Ferrari.
He also escaped from his own banzai move on Kimi Raikkonen in the closing stages - one the stewards deemed was worthy of 10 seconds being added to his elapsed race time - without damage. But as has been the party line this year, Rosberg is refusing to dream about a maiden title. He said: "I am quite liking my approach of seeing it on a weekend basis, so I don't have such thoughts."
4. Daniel Ricciardo is in fine spirits.
Daniel Ricciardo has been one of the star performers this season, and his victory here was certainly a popular one. It has been a long time coming for the Australian after he was robbed of a certain victory in Monaco following a Red Bull pit-stop gaffe, while a poorer tyre strategy than his teammate Max Verstappen in Spain saw him finish only third.
Asked how he may celebrate, Ricciardo said: "A few of us are flying tonight, so maybe a few little whiskies on the flight. There's some fine Japanese whisky in Tokyo, so we might have to have a day off."
5. Jolyon Palmer has plenty to offer.
Jolyon Palmer sent a timely reminder to his Renault bosses by scoring the first point of his career. A one-stop strategy paid off for the British rookie, who is out of contract at the end of the season, to cross the line in 10th.
He said: "It feels good, and I am really happy. I think the whole week has been really positive. I wish it was always so straightforward."