A serious accident involving Marussia's Jules Bianchi overshadowed Lewis Hamilton's victory in the Japanese Grand Prix.
Bianchi suffered a "severe" head injury in a crash that caused the race to be stopped early and is due to be put into intensive care after surgery.
Hamilton took his eighth win of the season after passing team-mate and title rival Nico Roberg for the lead around the outside of the fast Turn One.
Red Bull's Sebastian Vettel was third ahead of team-mate Daniel Ricciardo and McLaren's Jenson Button.
The race result seemed insignificant in the context of Bianchi's injuries, but Hamilton's eighth victory this season will surely be remembered as one of the greatest drives of his career. It extends his championship lead to 10 points with four races to go and 125 available.
The race was held in treacherous wet conditions as storms that preceded the approaching typhoon Phanfone hit Suzuka.
After a stuttering attempt to get the race under way, including a safety car start, a red flag after two laps, and a further eight laps under the safety car, it evolved into a duel between Hamilton and Rosberg.
Hamilton started the race in second, with Rosberg on pole, and once the race finally got under way, the Mercedes drivers were soon into the pits for intermediate tyres.
Rosberg stopped after three laps, Hamilton four, and then the battle between them began for real.
Hamilton was 2.2 seconds behind after their first stops, but began inching closer to Rosberg, piling on the pressure, and was within a second by lap 24, when conditions had improved enough for the DRS overtaking aid to be enabled.
Hamilton pressured Rosberg hard for five laps before making the decisive move at the start of lap 29.
He was close behind his team-mate as they exited the chicane, closed in with the help of the DRS and as Rosberg defended to the inside, Hamilton dived around the outside of Turn One to take the lead.
"That was bravery in the extreme," said BBC F1 co-commentator David Coulthard. "That is an overtake other drivers will remember."
Hamilton then pulled away quickly, sometimes extending his lead by more than two seconds a lap, until he was 16 seconds ahead when the race was red flagged again, and then declared over, after 44 laps.
The stoppage came as a result of Bianchi's crash, that happened as conditions worsened, with rain intensifying and light fading.
Bianchi's car hit water on the track at the fast uphill Dunlop corner and aquaplaned off at the same spot where recovery vehicles were attending the Sauber of Adrian Sutil, who crashed at the same spot the lap before.
Governing body the FIA said Bianchi was unconscious as he was taken to hospital.
Behind the Mercedes, Vettel took third on countback.
The German gained the position by passing McLaren's Button and the other Red Bull Ricciardo with an earlier stop for second set of intermediate tyres.
He lost it by stopping again for another set on lap 45 but was promoted back ahead of Ricciardo as a result of a rule that dictates the result is taken from the end of lap before the race was stopped.
Button was in the fight with the Red Bulls for a podium finish thanks to an inspired call to make an early stop for intermediate tyres just after the safety car pulled in on lap 10.
Williams drivers Valtteri Bottas and Felipe Massa were sixth and seventh, ahead of the Force India of Nico Hulkenberg, Jean-Eric Vergne's Toro Rosso and Hulkenberg's team-mate Sergio Perez.
Alonso, who had qualified fifth and is always strong in the wet, did not even get a chance to race on the weekend it emerged that he will leave Ferrari at the end of the year, two years before the end of his contract.
The double world champion's car ground to a halt with what appeared to be an electrical failure while the race was still under the safety car on lap five.