Rosberg's Monaco win began with a disputed qualifying lap

Monaco turned on one qualifying lap. Hamilton's final push for pole was ruined by yellow flags, which opened a debate over whether Rosberg had deliberately disrupted him. The stewards looked into it and the FIA found no evidence of wrongdoing, and Rosberg went on to win the race from pole.

Monaco is a street track where a single lap can decide the grid, and the 2014 race was no different. The episode also revived the tension between the two Mercedes drivers, which had been building since the Spanish and Bahrain races, and the Monaco result sent the title fight into a new phase.

Who won the 2014 Monaco Grand Prix?

Rosberg won the race from pole, with Hamilton second and Ricciardo third for Red Bull. It was Rosberg's second win of the season and the fifth of his career, and it returned him to the top of the drivers standings by four points.

Hamilton had led the championship into the weekend on 100 points, with Rosberg second and Alonso third. The result swung the title race back to his team-mate. Mercedes stretched its constructors lead to 141 points over Red Bull, while Ferrari held third.

One disputed pole lap, two safety cars and a Mercedes one-two that ended with Rosberg back on top of the drivers table.

Why was Rosberg's pole lap questioned?

Rosberg posted provisional pole with 1:15.989, 0.039 seconds ahead of Hamilton. He then locked his tyres at Mirabeau on his second and final quick lap and aborted it. The yellow flags that followed forced Hamilton to slow and ruined his own final lap, so the stewards investigated whether Rosberg had done it on purpose.

The stewards examined video evidence and telemetry from Mercedes, and the FIA concluded there was no evidence of wrongdoing by Rosberg. Tension between the two drivers was already high, because Hamilton had been found to have altered his settings in the final laps in Spain and Rosberg had done the same during the Bahrain race.

Rosberg kept his provisional pole, and the grid was set with him on the front row beside Hamilton, who was second.

What was the background to the Monaco round?

Before the weekend Hamilton led the drivers table with 100 points, ahead of Rosberg, and Alonso was third. Vettel was fourth on 45 points, seven ahead of his team-mate Ricciardo in fifth. Mercedes led the constructors with 197 points, Red Bull had 84, Ferrari 66, Force India 57 and Williams 46.

The circuit had been altered after the 2013 race. The track was resurfaced from the exit of Casino corner to the tunnel, the pit lane barrier and debris fencing were renewed, and the turn 12 energy-absorbing barrier was made more efficient. The work was done at night to limit disruption on the roads around the track.

Jenson Button expected the changes to create conditions similar to the 2012 United States Grand Prix, with low grip, and he thought the soft tyres would be hard to get working. Perez called the event difficult, and said it would be a new Monaco that was very interesting. Alonso called it a question mark for everybody and said the team that adapted its car best would have the edge.

How did practice and qualifying go?

Hamilton was fastest in the first practice session at 1:18.271, 0.032 seconds ahead of Rosberg. Chilton spun at Mirabeau and stopped early, and Alonso and Raikkonen both had moments at the tight corners around the harbour.

Hail fell before the second session, and the track was soaked. Teams kept their drivers in the garage for 45 minutes. Drivers first ran on intermediate tyres, but the surface dried quickly, and in the final ten minutes Alonso set 1:18.482 on dry slicks while Hamilton stayed fastest overall for the day. Friday was a day off, a feature unique to the Monaco Grand Prix.

On Saturday Hamilton set the fastest lap of the weekend at 1:16.758, half a tenth of a second clear of Ricciardo. Clear air was hard to find around the narrow circuit, and the drivers had taken longer than usual to bring their tyres up to temperature.

Qualifying was split into three parts. The first lasted 18 minutes and removed the drivers finishing 17th or lower, the second lasted 15 minutes and removed those in 11th to 16th places, and the final 12-minute session settled pole through to tenth. The 107 per cent rule applied to the first part.

Rosberg's first run in the final session put him on provisional pole, but Hamilton's chase was broken by yellow flags. Ricciardo qualified third, and Vettel lost use of his energy recovery system in the first session. Ferrari's Alonso and Raikkonen were fifth and sixth, and Vergne took seventh despite the yellow flags affecting his final lap.

Ericsson locked his rear tyres into Mirabeau and collided with Massa, and both drivers hit the barriers. Ericsson started from the pit lane and received two penalty points on his super licence. Gutierrez failed to get through the first session, and Bianchi was given a five-place penalty after a gearbox change.

In the first session Ricciardo was set to go faster but slower traffic delayed him, and Chilton stranded his Marussia after spinning at Mirabeau early on. Gutierrez went straight on at Sainte Devote, while Alonso locked a left-front tyre at Mirabeau and avoided damage. His team-mate Raikkonen spun leaving Sainte Devote but carried on.

Red Bull changed parts of Vettel's energy recovery system after the qualifying problems. He did not incur a penalty, but he was not allowed to use the replacement parts again until the Abu Dhabi Grand Prix.

Rosberg's hand clutch was also replaced, because the one he used in qualifying had burned out after his error at Mirabeau. Hulkenberg was the fastest driver not to reach the final part, in eleventh, while Kobayashi used super-soft tyres on his first two timed laps in the final part, adjusted his front wing and could not improve.

Ericsson started from the pit lane after his collision with Massa in the first part of qualifying. That collision also prevented Massa from taking part in the second session.

How did the race unfold from the start?

Maldonado did not start because of a fuel pump failure on the grid. Rosberg led into the first corner with Hamilton second, and Vettel stayed third while Raikkonen moved from sixth to fourth. Alonso was held up behind Ricciardo on the opening lap.

Perez spun after contact with Button leaving Mirabeau, damaging his car's suspension, and he had further contact with Sutil that ended his race. The incident blocked the track, and a safety car came out so marshals could move the stranded car onto the run-off area. Rosberg led again when the safety car left at the end of lap three.

Vettel's turbocharger failed, and the field passed him. He made a pit stop and complained that he was stuck in first gear. Red Bull told him to retire on lap seven after his turbocharger restarted. Kvyat retired in the pit lane on lap 11 with an exhaust fault.

Rosberg locked his tyres into Mirabeau again on lap 18 but avoided the escape road. Then the stewards gave Chilton, Ericsson and Gutierrez five-second stop-and-go penalties for starting out of position. Hamilton began to lap faster than his team-mate, but Rosberg responded with a faster lap of his own.

Sutil's car went light over the crest leaving the tunnel on lap 24 and speared into the inside wall before the Novelle chicane. He was unhurt, but debris meant another safety car. Every driver except Massa pitted for new tyres under it. Hamilton asked his team whether he should stop, was told no, and fell back to avoid waiting behind his team-mate.

Vergne was released in front of Magnussen, who had to swerve, and the stewards investigated. Raikkonen made a second stop for a punctured tyre after Chilton's front wing hit his rear wheel at Mirabeau. The race restarted with Rosberg leading Hamilton, and Hulkenberg overtook Magnussen on the inside at Portier.

Vergne was given a drive-through for his unsafe pit release and served it four laps later. Bianchi and Kobayashi made contact several times, and Bianchi finally passed on the outside at Rasacasse. Massa made his only stop on lap 45 and rejoined ahead of Bianchi.

How did the race finish?

Rosberg won after Hamilton got dirt in his eye in the closing laps. Mercedes had asked Rosberg to use longer gears to save fuel, which left him defending from Hamilton after slowing. Hamilton closed up but could not pass his team-mate into the tunnel.

Rosberg was told to conserve fuel, while Hamilton was told he did not need to do so. The difference in instructions was a clear sign of how tight the title fight had become. Rosberg crossed the line first, and his second win of the year put him back at the top of the drivers standings.

The race began under a dry, overcast sky, with a 20 per cent chance of rain forecast. Maldonado was unable to take the start after a fuel pump failure on the grid. The stewards investigated the first-lap incident between Perez and Button.

As drivers struggled to keep heat in their tyres, the gap between the two Mercedes drivers varied, but both stayed well clear of the rest of the field.

Race facts at a glance

What did the result mean for the championship?

Rosberg regained the drivers lead by four points over Hamilton, and Alonso remained third. Ricciardo's third place moved him past Vettel, and the constructors gap over Red Bull grew to 141 points, with 13 races left in the season.

Force India kept fourth in the constructors standings and McLaren overtook Williams for fifth. With 13 races left, the two Mercedes drivers had a points gap that was small enough for either to take the title, and Monaco showed how a single lap can change that picture.