How Hamilton won at Sochi while a last-lap collision decided the podium

Lewis Hamilton took the flag at the Sochi Autodrom on 11 October 2015, his ninth win of the season. The race is remembered as much for a late collision between Valtteri Bottas and Kimi Raikkonen, which took both of them out of the points and handed Sergio Perez third place for Force India. Pole sitter Nico Rosberg retired early with a locked throttle.

What was the championship picture going into Sochi?

Hamilton led the drivers' championship by 48 points over Rosberg, with Sebastian Vettel a further 11 points back in third. Mercedes led the constructors' table on 506 points, 169 ahead of Ferrari, and Williams were a further 129 points behind the Italian team in third.

This was only the second time the Russian Grand Prix had counted towards the world championship, and it came in the fifteenth round of the season.Pirelli named the yellow-banded soft as prime and the red-banded supersoft as option, because tyre degradation had been lower than expected at the previous year's race. Last year Rosberg had completed 52 of the 53 laps on the white-banded medium tyre on his way to second place, and drivers had set fast laps all race on a one-stop strategy.

Fernando Alonso started from the back after a thirty-five-place grid penalty for changing engine parts. Honda gave him an upgraded engine built from the last of its in-season development tokens, but Jenson Button kept the older specification because Honda had only one upgraded unit to spare.

Roberto Merhi replaced Alexander Rossi at Marussia, because Rossi was sitting out Sochi and Abu Dhabi under his five-race contract. Jolyon Palmer took Romain Grosjean's place at Lotus for the first practice session, for the tenth time that season.

The race was won by Hamilton, but the podium was decided by a collision on the last lap.

How did practice go in the wet?

Practice was badly disrupted. Diesel spilt on the track kept the cars in the garage until very late in the opening session, and heavy rain in the second session meant only eight drivers set timed laps. Felipe Massa was fastest in that session, at 2:00.458.

Nico Hulkenberg topped the first session for Force India, ahead of Rosberg and Vettel. Hamilton lost the car on his final timed lap and finished seventh, while Marcus Ericsson was confined to the sidelines by an engine problem.

Water had been used to clear the surface, so most drivers ran their first laps on intermediates, while both Williams cars went out on full wets. Bottas spun on them as he entered the pit lane. Alonso was the first to use slick tyres once the track dried, and the session ended with a rush of cars on track.

The second session was the one Alonso used most. He ran twelve laps after an engine change, and neither Lotus nor Marussia ran in that session at all.

The third session, on Saturday, was halted by a huge crash for Carlos Sainz Jr at turn 13. He hit a wall and then the barriers, burying the nose of his car, and he was taken to hospital uninjured. The guardrail behind the barriers collapsed, and practice was not resumed.

Rosberg's 1:38.561 stood as the fastest lap of the session. Bottas trailed by seven-tenths of a second, and Hamilton was a tenth further back. Verstappen finished the session 17th after spinning in the final corner.

How did Rosberg set pole on a damp track?

Rosberg set pole at 1m37.113 and beat his teammate by three-tenths of a second, denying Hamilton a fiftieth career pole. Only the two Mercedes drivers went through the first part without needing the faster, softer tyres, and Rosberg was fastest of them in that part, ahead of Bottas and Hamilton.

Carlos Sainz Jr set no time in qualifying after his practice crash, but the stewards allowed him to race. He was given a twenty-place grid penalty for changes to his power unit and a gearbox replacement. Both Marussia drivers were eliminated in the first part, along with Marcus Ericsson of Sauber and Fernando Alonso.

In the second part the two Mercedes exchanged new track records, with Rosberg, then Hamilton, then Rosberg again going quickest. Bottas was the fastest non-Mercedes runner, while Felipe Massa was held up in traffic and missed Q3. Maldonado, Button, Nasr and Kvyat fell in that part, with Kvyat and Nasr bettered by a late lap from Max Verstappen.

In the final part Rosberg was fastest again, with Bottas third, marginally ahead of Vettel. Kimi Raikkonen was fifth after making a mistake at turn 13, and the two Force India cars of Hulkenberg and Perez qualified sixth and seventh. Hamilton ran off the track at turn 13 during his second fast lap, which left him unable to answer Rosberg.

How did the race start?

Rosberg led away from Hamilton, but further back Hulkenberg spun into turn two and tagged Verstappen and Ericsson. Verstappen had a puncture, while Hulkenberg and Ericsson were out on the spot, which brought out the safety car. Racing resumed at the end of lap 3.

Raikkonen and Kvyat made good starts and gained two and four places. Bottas then slipped past Raikkonen for third. By lap 7 Sainz had climbed to 14th, and Massa had come through from 15th on the grid to ninth. Ricciardo and Sainz then fought over tenth place, and Ricciardo came out on top and kept it.

Rosberg retired at the end of the seventh lap with a locked throttle, handing the lead to championship leader Hamilton. Maldonado moved ahead of Button for tenth on lap 10, and Hamilton began to stretch his lead over Bottas.

A second safety car came out on lap 12, when Romain Grosjean crashed at turn three and his Lotus was heavily damaged. The debris kept the safety car out until lap 17. When racing resumed, Vettel went for Raikkonen, who ran wide at turn two and gave the place back.

What decided the middle of the race?

Hamilton extended his lead over Bottas to 7.5 seconds by lap 24, while Vettel closed in on the Finn. Most of the front runners pitted from lap 25. Sainz was given a five-second penalty for crossing the white line as he left the pit lane, which he would have to take during his second stop.

The first leader to make his stop was Bottas, on lap 27, and he rejoined in traffic. Vettel stayed out longer and emerged ahead of him on lap 31. Raikkonen pitted a lap later, and Hamilton came in one lap after that and kept the lead without trouble.

Perez had pitted early under the safety car and was running third, with Ricciardo fourth. By lap 43 Ricciardo, Bottas and Raikkonen were all close to the Force India. On lap 45 Bottas used DRS to pass Ricciardo, and Raikkonen tried to follow one lap later, ran wide and handed the place back.

Verstappen had moved up to twelfth by lap 20 after his start-line puncture. On lap 37 Raikkonen used DRS to pass Bottas for fifth, but the Williams driver got the place straight back at the next corner. Bottas and Ricciardo still received classified finishes, having covered over 90% of the distance.

Sainz retired on lap 47 after a brake failure, and he spun off with his rear wing lost. A marshal went out to retrieve the wing under racing conditions, and Vettel nearly collided with him, calling the man one very brave Russian. Ricciardo retired on lap 49 with a suspension failure just after Raikkonen had passed him.

How did the last-lap collision decide the podium?

On lap 52 Bottas moved ahead of Perez into third, and Raikkonen went past the Force India as well. A few corners later on the final lap the two drivers collided. Bottas retired, Raikkonen's Ferrari was badly damaged, and Perez regained third to give Force India its first podium of the season.

Vettel closed on Hamilton, who was suffering from a compromised rear wing, possibly from debris in the slot gap. Hamilton had led every lap since Rosberg's retirement on lap 7, and he held on to take his ninth win, with Vettel second. Perez admitted he had been very upset with his own race until the final lap, and he called it the best moment of his career.

Sochi 2015 at a glance

What were the penalties and the points?

Raikkonen was demoted from fifth to eighth for the collision with Bottas, which cut his points to four rather than ten. Alonso, who had originally finished tenth, picked up a five-second penalty for going beyond the track limits, which moved Verstappen up to tenth. The result secured Mercedes a second straight constructors' title.

Sainz also received a five-second time penalty after the race, although he had already retired. Mercedes extended their constructors' lead to 172 points, and Williams stayed third on 220 points, 71 ahead of Red Bull. In the drivers' table Hamilton's lead over Vettel grew to 66 points, and Rosberg slipped to third on 229 points, seven behind Vettel.

What did the drivers say afterwards?

Raikkonen said he would make the same move again, and he showed no regret about it. Bottas disagreed, saying he did not think it was a racing incident, since he had not seen anyone and was hit while he was in front. He added that he should have been on the podium, not left with zero points.

Eddie Jordan conducted the podium interviews. Hamilton said the championship was not done and dusted, while Vettel criticised the slow pace Hamilton had kept at the restart, arguing that the field could have been bunched up far earlier.

Sainz said he felt dizzy in the early laps after his practice crash, but that the feeling passed after lap 10. Grosjean said the seat of his car had broken on impact, calling it the biggest impact he had felt in quite a while, and he credited the car's safety features with getting him out unharmed.