Nico Rosberg won the Monaco Grand Prix from pole position on Sunday to take the overall championship lead from his teammate Lewis Hamilton, who came in second to give Mercedes a fifth straight 1-2 finish.
Hamilton appeared unhappy before, during and after the race in what promises to be a thrilling fight both on and off the track between the two drivers for the remaining 13 GPs.
Rosberg clinched his second victory of the season and fifth of his career, making a strong start and holding off Hamilton to repeat his maiden GP win from pole here in Monaco last year. Rosberg now leads Hamilton by four points: 122-118.
"The pressure was on all the way but I kept it cool and was able to win," said the German, who celebrated by hugging his team engineers.
"It's a special win, definitely, because Lewis has had the momentum with results and I managed to do that somewhat this weekend," said Rosberg, who struggled to manage his fuel load at times. "Fuel was very critical and caught me off guard a bit."
Rosberg finished 9.2 seconds ahead of Hamilton, who was just 0.4 faster than Daniel Ricciardo. The Red Bull driver was unable to get past Hamilton on a track that is the most difficult to overtake on in Formula One. Spaniard Fernando Alonso was fourth for Ferrari.
Four-time defending champion Sebastian Vettel's frustrating season with Red Bull continued as he abandoned early with a power unit failure.
Mercedes has taken every pole position so far this season: four for Hamilton and two for Rosberg, who won the season's opening race in Australia.
But the relationship between the childhood karting rivals seems to be deteriorating rapidly. They did not appear to shake hands after the race, and Hamilton looked visibly tense in the post-match race conference as he sat next to Rosberg.
"I felt I was very strong today," said Hamilton, who complained that his visibility was impaired by some dirt in his left eye. "Racing with one eye is virtually impossible to do. I was trying to open up my visor, which made it worse. I drove with my all heart and did everything I could do — fairly. I feel I drove fairly all weekend."
That comment looked like a veiled swipe at Rosberg for his controversial driving in qualifying.
During the race a tense Hamilton even snapped back at his team when told that Ricciardo was closing the gap on him.
"I don't care about Ricciardo, what's the gap to Nico?" said Hamilton, who earlier complained about the timing of a pit stop to underline what has been a tense weekend within Mercedes.
Hamilton was made to care about Ricciardo by the end and spent the final four laps blocking the Australian. It was a second straight third-place finish for the impressive Ricciardo, who is now ahead of Vettel, his more illustrious teammate.
"It is thrilling to be on the podium here in Monaco," Ricciardo said. "The start was not good, not what I wanted, actually dropped back to fifth. Third was the best we could do, so not a bad day."
Hamilton did pressure Rosberg at times and would certainly have attacked more on another track. But Monaco's 78-lap circuit — which has the slowest average speed on the F1 calendar —meant Rosberg's position was relatively safe throughout, unless Hamilton tried a risky move that could have made him crash.
Overtaking is so tough that 10 of the past 11 winners have done so from pole, the exception being Hamilton in 2008, the year he won the title.
Qualifying first for the race came amid controversial circumstances for Rosberg, who was cleared by stewards of any wrongdoing after making a late error that led to a yellow flag and curtailed Hamilton's chances of beating his time with less than one minute remaining in Saturday's session.
It was an incident that fueled the growing rivalry between the two runaway leaders in the overall standings. The British driver insinuated afterward that he would get revenge and evoked memories of the bitter rivalry between the late Ayrton Senna of Brazil and Frenchman Alain Prost when they raced for McLaren in the late 1980s.
Hamilton, who three days ago had taken the astonishing step of questioning his own teammate's hunger with somewhat disparaging comments, even intimated that he would "take a page out of his book" when referring to how Senna dealt with his conflict with Prost.
The safety car came out on lap one after Sergio Perez was bumped off the track by his former teammate Jenson Button's McLaren on the first lap, smacking into the barriers at the Mirabeau turn.
Vettel, who won 13 races last season, pitted after a few laps. Although he went back out, his team ordered him back in on lap eight.
The safety car was the only threat to Rosberg's momentum, and it came out again on lap 26 when German driver Adrian Sutil's Sauber went into the barriers on the run down to the chicane, sending debris flying onto the track. Mercedes pitted both their cars, although Hamilton seemed unhappy about it.
"I can't believe we just had to pit," Hamilton said. "Can you just inform me of what options I have?" He even sounded suspicious when he said : "We should have pitted on that lap (before) — but I knew you wouldn't call me in guys."
Ironically, though, the stop worked in Hamilton's favor, as he trimmed Rosberg's lead to 0.8 seconds — but that was as close as he got.