Why the 2015 Chinese Grand Prix ended behind the safety car

Lewis Hamilton won the 2015 Chinese Grand Prix at the Shanghai International Circuit on 12 April, his second win of the season. Nico Rosberg finished second for Mercedes and Sebastian Vettel took third for Ferrari. The race ended under a safety car, and the result was overshadowed by a public argument between the two Mercedes drivers.

Could Ferrari challenge Mercedes in Shanghai?

Ferrari had surprised the field by winning in Malaysia two weeks earlier, when Vettel took the chequered flag. Engineers expected cooler track temperatures in China, and that raised doubts about the Italian team's pace, because its tyres had lasted better in the Malaysian heat.

Hamilton arrived as the defending race winner with a three-point lead over Vettel in the drivers' standings. Marussia hoped to run both of its cars for the whole weekend after Will Stevens failed to start in Malaysia, and all ten teams lined up in Shanghai.

Pirelli brought its white-banded medium tyre as the prime choice and the yellow-banded soft as the option, the same pairing it had used in 2014.

A late safety car flattened the finish, and a teammate's public row took over the post-race talk.

What did practice show?

Practice came in three blocks: a pair of 1.5-hour runs on Friday, then a single hour on Saturday ahead of qualifying. Hamilton topped all three, and on Friday morning he was more than half a second clear of Rosberg. Vettel was almost half a second behind Hamilton in the Friday afternoon session.

Lotus gave a seat to test driver Jolyon Palmer in place of Romain Grosjean for that first session, and Palmer ended up six-tenths of a second adrift of Pastor Maldonado. Felipe Massa spun his Williams at turn 14 and hit the barrier, bringing out a red flag for a while.

The session also had an odd interruption. A local man ran across the main straight, reached the pit lane and then made it into the Ferrari garage, where he reportedly said he wanted to try a car. Security stopped him.

Massa reported smoke in his cockpit on both Friday and Saturday. The cause was the new titanium plates under the cars, which threw sparks when they bounced over bumps. McLaren struggled on Saturday too: Fernando Alonso halted just after starting his installation lap, and Button was summoned to the pit lane over a similar engine concern.

How did qualifying set the grid?

Hamilton took pole position, his 41st in Formula One and his third in a row, beating Rosberg by 0.04 seconds. Vettel was third, ahead of the two Williams cars, while Kimi Raikkonen started sixth after struggling with the handling of his car through the first part of the lap.

Qualifying ran in three parts of 18, 15 and 12 minutes, with five drivers eliminated after each of the first two. It began at 15:00 local time, which is UTC+8. Mercedes was the only team to run the medium tyre in the first part, while everybody else chose the faster soft.

Hulkenberg, who was due to start 16th, failed to reach the second part along with both Marussia cars and both McLarens. In the second part Hamilton was fastest, three-tenths ahead of Rosberg, and Kvyat suffered engine problems that kept him out of the top ten shootout.

Rosberg was frustrated with the result. He lamented that the team had put him under unnecessary pressure by telling him to go faster on his last warm-up lap.

Why did Rosberg and Hamilton fall out?

Rosberg complained over the radio that Hamilton was driving too slowly in front of him. He said he could not follow closely without damaging his tyres, and that the air coming off the back of Hamilton's car was wearing them out faster. The pit wall then asked Hamilton to pick up the pace.

Ferrari, for its part, still had a spare set of new tyres that it had kept back from qualifying. That made the Mercedes pair careful about managing their tyres to cover an attack, and it turned the middle of the race into a test of nerve.

After the race Hamilton said he had not been controlling Rosberg's race, only his own. Rosberg answered that it was interesting to hear Hamilton had been thinking only about himself, and that this had compromised his race.

Niki Lauda, the Mercedes non-executive chairman, sided with Hamilton. He said all top drivers are selfish, called them egocentric, and argued that this is the only way to win a championship.

How did the race unfold?

Hamilton led from pole and kept his advantage in the middle of the race. Rosberg was second, Vettel third, and Raikkonen made up ground over the final stint. The late safety car ended the chance of a Ferrari duel for third.

On the opening lap Raikkonen went around both Williams to take fourth, and Rosberg kept Vettel behind him for second. Sainz spun his Toro Rosso on lap two and dropped down the order. The first retirement came on lap ten, when Hulkenberg's gearbox failed and his Force India ended up in the gravel.

Ferrari tried an undercut by pitting Vettel early on lap 13. An undercut means a chasing car stops early to use fresh tyres and jump a rival without a pass on track. Mercedes responded by pitting Rosberg the next lap, which kept him ahead of Vettel.

Kvyat's afternoon ended on lap 17, when smoke began pouring from his Red Bull because the engine had failed. By lap 54 Hamilton had a 10.06-second cushion over Rosberg, and Vettel trailed Rosberg by another 12.12 seconds.

Raikkonen rejoined 4.84 seconds down on Vettel after his last stop on lap 35, and his rubber was four laps newer than his teammate's. By lap 54 he had closed to within 1.37 seconds of Vettel and was setting up a battle for the final podium place.

That battle never happened. Max Verstappen's Toro Rosso suffered a transmission failure and stopped on the start-finish straight. The safety car came out for the final two laps, so the race ended under caution and the chance of a close finish disappeared.

Hamilton said afterwards that the late caution was a kind of anti-climax after a race he had enjoyed. He had been ahead for most of the second half, and the safety car flattened the finish that many fans had been waiting for.

Who had a difficult race?

Pastor Maldonado had a difficult afternoon. He missed the pit entry on lap 33 and lost several places, spun on lap 39 while trying to recover time, and then collided with Button on lap 48 after a long battle for position. He retired a few laps later with rear brake failure.

The stewards placed the blame on Button for that collision. Button had originally finished 13th, but a five-second post-race time penalty followed. Merhi was also given five seconds, for dropping below the lap time he was required to hold under the safety car.

Verstappen was classified in the end, because he had completed over 90 percent of the race distance.

Why is the race still talked about?

The race is usually remembered for the row rather than the podium. Two Mercedes drivers disagreed publicly about pace and team instructions, and the team's non-executive chairman openly defended the winner. That made Shanghai a weekend about tension inside the strongest team on the grid.

Edwin Moses, the two-time Olympic 400 metres hurdles champion, conducted the podium interviews. Hamilton credited the team with a superb effort, and he called the late caution a letdown after a race he had enjoyed.