Fernando is the new World Championship leader after winning a heavily weather-affected South Korean Grand Prix which saw neither Red Bull driver finish.
The Spanish double world champion capitalised on Mark Webber crashing out on a drying track and Sebastian Vettel, who led from the start, being forced out with an engine problem.
Briton Lewis Hamilton finished second ahead of Felipe Massa and now stands third in the driver’s table with 210 points, while Webber has 220 and Alonso 231 after his 25-point haul. There are two races remaining in the season.
The inaugural Korean GP, already controversial due to delays in construction which saw it almost scrapped from the calendar, was frustrating early on but delivered high drama by its conclusion.
Those delays had been due to torrential rains which have deeply affected Korea’s economy - and it was rain again which threatened to ruin raceday for the huge number of fans who turned out in the wasteland setting of Yeongam.
First of all the light, continuous downpour which began in the lead-up to the race caused a 10-minute delay as race director Charlie Whiting pondered whether to start the race under normal or safety car conditions.
Opting for the latter, his choice was shown to be a wise one as the drivers complained of a complete lack of visibility as the newly-laid tarmac held surface water which produced a massive amount of spray.
The cars tiptoed around three laps before a red flag signalled that conditions were too dangerous to continue and the grid lined up again to await an improvement.
After a delay of over 45 minutes – with the race clock stopped around seven minutes in – they pulled away a second time, but the safety car did not come in for another 13 laps. Hamilton could not understand the hesitancy, but the majority of drivers had reservations.
Ironically, once they did begin Hamilton was passed by Nico Rosberg for fourth.
There were some minor offs before Webber turned his Red Bull around and smashed it into the barriers. Alonso came through before the Australian’s car slowly slipped backwards across the circuit, collecting Rosberg.
Vettel had been flying at the front but saw his lead wiped out by the safety car, with Ferrari’s Massa, Jenson Button and an attacking Michael Schumacher following Alonso and Hamilton.
The seven-times world champion slipstreamed Button for fifth three laps after racing conditions were resumed.
There were retirements down the field, with Sebastien Buemi at fault in sideswiping Timo Glock, which brought out further safety cars – but Vettel never looked in danger of relinquishing his lead having started from pole.
With 23 laps remaining, and sunset as much a concern as the two-hour time limit, Alonso lost a place to Hamilton after a mechanic dropped a wheel nut. Vettel and the Briton had also both pitted with the safety car just out.
When it came in Hamilton ran wide to allow the Spaniard through, and suddenly had Massa all over his back end instead; however he fended the Brazilian off and pulled away over the following laps.
Button lost three places and stood 15th after Adrian Sutil took advantage of a pair of fighting cars ahead of them to force the Englishman off the track.
Vitaly Petrov, seeking to impress his bosses at Renault and earn a new deal, crashed into the tyre barriers from 11th position with 14 laps left.
Five laps later the Korean crowd were left gasping when Vettel, leading Alonso down the straight, suddenly lost power and his engine began to billow smoke.
He looked as disconsolate as team-mate Webber had before him when returning to the pits, perhaps visualising the title slipping away.
Alonso, who had been majestic throughout, took full advantage to see out the race without incident despite the darkness descending upon Yeongam - building a healthy lead over Hamilton who had concerns over his front tyres with the championship also still there for him.
He too guided his car home, but McLaren team-mate Button is not expected to defend his title any longer after finishing a disappointing 12th. He has 189 points, behind Vettel who has 206.
Finishing outside the podium but in the points were Schumacher, Robert Kubica, Vitantonio Liuzzi, Rubens Barrichello, Kamui Kobayashi, Nick Heidfeld and Nico Hulkenberg.
Nine drivers failed to finish: Rosberg, Webber, Buemi, Petrov, Vettel, Sutil, Glock, Lucas di Grassi and Jarno Trulli.