Fernando Alonso stretched his championship advantage to 34 points after claiming his third Formula One victory of the season in the German Grand Prix.

A campaign that started with a record seven different winners in the first seven races has now seen Ferrari star Alonso take a stranglehold by winning two of the last three.

Behind the 30-year-old reigning world champion Sebastian Vettel, on home soil at Hockenheim, finished second for Red Bull ahead of Jenson Button in his McLaren.

Vettel, however, was later demoted to fifth for a penultimate-lap move on Button as he ran off the circuit to complete the manoeuvre. Button moved to second.

As for team-mate Lewis Hamilton, on the occasion of his 100th grands prix, it was one to forget for the 27-year-old, who has now collected a meagre four points from the last three races after retiring 10 laps from home.

Like Button of late, from winning in Canada and leading the way, Hamilton's championship challenge has rapidly gone off the rails to drop to 62 points behind Alonso.

On this occasion a slow start off the line was a pre-cursor to his downfall as Hamilton lost two places going into turn one.

But it was what occurred behind him that ultimately proved his undoing as Felipe Massa ran into the back of Kimi Raikkonen in his Lotus, dislodging the front wing of the Ferrari.

That sent shards of carbon fibre on to the track, yet there was no safety car, so when Hamilton made his way through the first corner at the start of lap two he collected a puncture.

It resulted in a long, slow run to the pits for a change of tyres, and although Hamilton felt he would have to retire then, his team said otherwise, dropping back to 22nd.

Hamilton, though, would later have a significant say as in making his second stop after 33 laps - the halfway point - Hamilton was lapped by leading duo Alonso and Vettel.

It resulted in a radio message from McLaren telling Hamilton not to hold up Button three seconds behind him.

It was a message Hamilton did not need to heed because on fresh rubber, and although effectively a backmarker, given the speed of his McLaren he was able to attack first Vettel and then harry Alonso.

When Hamilton made his move on Vettel into the hairpin at the end of the DRS zone to un-lap himself, the German made his unhappiness felt by waving his hand at the Briton.

That allowed Hamilton to then loom large in the wing mirrors of Alonso, making enough of a nuisance of himself that McLaren were able to pit Button after 40 laps.

Unsurprisingly Ferrari and Red Bull reacted by bringing in Alonso and Vettel a lap later, however, Button did enough on one lap to pick off the latter to move up to second.

Vettel did attempt an immediate pass into the hairpin using DRS, but Button defended brilliantly, albeit picking up a flat-spot on the front-right tyre.

It was a case of then playing a waiting game for Button because, despite closing to within a second of Alonso, he was unable to make any move on the Spaniard.

Instead, Alonso pulled away from Button over the closing laps, who in turn fell back into the clutches of Vettel, who was able to make his move on lap 66 to finish runner-up.

Behind the leading trio Raikkonen was fourth (later moved to third), followed by the Saubers of Kamui Kobayashi and Sergio Perez, with Michael Schumacher seventh in his Mercedes.

Mark Webber could only finish where he started in his Red Bull - eighth - to fall to 34 points behind Alonso, with Vettel a further two points behind.

Force India's Nico Hulkenberg and Mercedes' Nico Rosberg completed the top 10, the latter from 22nd on the grid, with Paul di Resta just outside the points in 11th in his Force India.

After savouring the champagne, and being interviewed by triple world champion Niki Lauda on the podium, Alonso said: "It was tough, not an easy race.

"Maybe we were not the quickest, but we were quite competitive, enough to maintain the lead, with some good strategy from the team.

"After the second stop, when I was coming under pressure, the car was good enough under traction and in top speed to control the race."

Vettel, however, was fuming with Hamilton for when he unlapped himself as he said: "I didn't see the point of that.

"It was a bit stupid to disturb the leaders. If he wanted to go fast he should have dropped back, found a gap and go fast then.

"Overall, I'm not entirely happy."