Nico Rosberg won the Monaco Grand Prix from pole position to take the overall championship lead from his teammate Lewis Hamilton, who came second to give Mercedes a fifth straight one-two finish.
The German driver 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.
"The pressure was on all the way but I kept it cool and was able to win,'' said Rosberg, who celebrated by hugging his team engineers.
| Driver Points
1 Nico Rosberg 122
2 Lewis Hamilton 118
3 Fernando Alonso 61
4 Daniel Ricciardo 54
5 Nico Hulkenberg 47
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.
Four-time defending champion Sebastian Vettel's frustrating season with Red Bull continued as he abandoned early with a power unit failure.
Mercedes has also taken every pole position so far this season: four for Hamilton and two for Rosberg, who won the season's opening race in Australia.
"I felt I was very strong today,'' said Hamilton, who complained that his visibility was impaired by some dirt in his left eye.
But Hamilton 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.
Hamilton did pressure Rosberg at times, even trimming his lead back to 0.8 seconds and would certainly have attacked more on another track.
Difficult attacking circuit
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 fuelled the growing rivalry between the two runaway leaders in the overall standings, with Hamilton insinuating afterwards that he would get revenge and evoking 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.