Alonso's victory sets up drama in finale as the Red Bull pair fail to finish and Lewis Hamilton is second in a chaotic debut Korean Grand Prix.
An F1 showdown in the capital looks certain
YEONGAM, SOUTH KOREA //The 2010 Formula One season is edging ever closer to a thrilling Abu Dhabi finale in the wake of yesterday's topsy-turvy Korean Grand Prix.
The points lead changed hands three times in quick succession as a combination of treacherous conditions and miserable luck sidelined Mark Webber and Sebastian Vettel, the Red Bull Renault drivers, leaving Fernando Alonso to score his fifth win of the campaign for Ferrari.
It was a snapshot of the season as a whole.
The Spaniard's victory put him 11 points clear of Webber, with Lewis Hamilton, yesterday's runner-up, and Vettel 21 and 25 adrift respectively.
Jenson Button retains a mathematical chance of a successful title defence, but with 42 points to make up - and only 50 still available - the Englishman's hopes are almost as remote as the South Korean town of Yeongam, host for yesterday's landmark race.
For months, there was speculation that the new venue would not be ready - and although it was completed just in time, it looked for a moment that the weather might decimate the event.
Persistent drizzle morphed into heavy rain just before the scheduled start and there was a 10-minute delay before the field set off behind the safety car.
Even at reduced pace, however, drivers struggled to keep their cars on track and the red flag was shown on lap three.
Alonso described conditions as "the worst I have experienced in a racing car".
It would be 49 minutes before the race resumed, again behind the safety car, and the soggy procession continued until the end of lap 17, when the field was released with Vettel leading from Webber and Alonso.
Hamilton ran fourth, but lost a place to Nico Rosberg, whose Mercedes GP team had cannily softened the suspension on their cars during the interruption, to make them more compliant in the wet.
Most teams believed conditions would improve, but Mercedes did not.
Webber lasted only two laps before using a little too much kerb at Turn 12, whereupon his car looped around and slithered back across the circuit into the path of Rosberg.
Both cars were out on the spot, Hamilton moved up to third and the safety car reappeared while the mess was cleared.
Vettel was absolutely mighty when the race restarted at the end of lap 23, bounding the potentially treacherous kerbs at Turn 18 and gaining a big enough advantage to immunise himself against Alonso's advances.
He edged away once more until lap 31, when the safety car was dispatched yet again after Sébastien Buemi (Toro Rosso) clattered into Timo Glock (Virgin) at Turn Three.
Both drivers retired and Buemi was given a five-place grid penalty in Brazil for causing an avoidable accident.
Vettel and Alonso had passed the pit entry when the race was neutralised, but Hamilton and the following drivers all made a timely switch to intermediate rubber.
The two leaders followed suit next time around, but Ferrari had a problem with Alonso's front right wheel nut and the delay dropped him to third, behind Hamilton. That potential hurdle was resolved within seconds of the restart, on lap 34, when the Englishman locked his brakes and slithered wide at Turn One.
That appeared to have settled the issue, until Vettel slowed suddenly as he passed the pits for the 45th time.
His engine let go without warning and he pulled over at the exit of Turn One, his race and, possibly, his title hopes expiring in a plume of smoke.
Alonso went on to win from Hamilton and the distant Felipe Massa, who faded after a promising start in his Ferrari.
If the Spaniard scores one more point than Vettel in Brazil, the German will be out of the title race, but then the quick sweeps of Interlagos are likely to be tailored to the Red Bulls' renowned aerodynamic strengths.
"We will fight to the final corner of the final race," Stefano Domenicali, the Ferrari sporting director, said, "and I think we might have to."
• Fernando Alonso, 231 points
A win and a third in last two races would give him the title
• Mark Webber, 220 points
Two wins would guarantee he takes the title
• Lewis Hamilton, 210 points
Needs two wins, and for Alonso to score no more than 28 points
•Sebastian Vettel, 206 points
Needs two wins, and for Alonso to score no more than 24 points