Red Bull had earlier headed the time sheets over one second quicker than third-quickest Robert Kubica, but Ferrari showed promise after an initial battle between Sebastian Vettel and Mark Webber.
VettelÃ¢â‚¬â„¢s marker of 1:20.087 on BridgestoneÃ¢â‚¬â„¢s super soft compound was unbeatable, and the German almost went quicker, but traffic hindered what should have been his quickest time.
Alonso managed a time of 1:20.584, just 0.013 quicker than WebberÃ¢â‚¬â„¢s best time, while team-mate Felipe Massa lapped fourth-quickest as the only other driver within a second of VettelÃ¢â‚¬â„¢s time.
As was the case at Hockenheim, Ferrari have positioned themselves as the only rivals to Red Bull for SaturdayÃ¢â‚¬â„¢s qualifying.
Vitaly Petrov was best of the rest for Renault to take fifth ahead of McLarenÃ¢â‚¬â„¢s Lewis Hamilton, who continued to concentrate on heavy fuel runs.
WilliamsÃ¢â‚¬â„¢ Nico HÃƒÂ¼lkenberg continued his impressive running to take eighth ahead of Jenson Button and Michael Schumacher.
McLarenÃ¢â‚¬â„¢s drivers were both downbeat at their inability to keep pace with their rivals as Red Bull and Ferrari continue to show their dominance on the maximum downforce circuit.
For McLaren, it is a case of damage limitation on a track where they are not expecting to make too much of an impact, barring any incidents involving the Red Bull.
Hamilton said: Ã¢â‚¬Å“The car was the best I’ve ever driven around here.
“It felt really great through the corners, but, even so, we’re losing quite a bit of time in the middle sector, and a couple of tenths in the first and third sectors, too.
Ã¢â‚¬Å“I think we’re pretty much getting the best out of the package we haveÃ¢â‚¬â€œwe’re dialling-in the set-up pretty effectivelyÃ¢â‚¬â€œbut there’s still maybe a few tenths to come.
“So we know we’ve got a lot of work to do: this weekend is really about scoring as many points as we can, and hoping the guys ahead run into trouble.
He added: Ã¢â‚¬Å“It’s going to be tough, but we’ve got to take the rough with the smooth and stay focused.
“And we’ll do that, no doubt about it. As always, of course, I’ll be pushing as hard as I can.Ã¢â‚¬Â
Pedro de la Rosa had a great outing for Sauber to take 11th just 0.035 seconds ahead of Rubens Barrichello, and four-tenths ahead of team-mate Kamui Kobayashi in 14th.
Force IndiaÃ¢â‚¬â„¢s Adrian SutilÃ¢â‚¬â€running with a blown diffuser for the first timeÃ¢â‚¬â€could only manage 16th-quickest, sixth tenths faster than team-mate Vitantonio Liuzzi running without it.
Sutil said: Ã¢â‚¬Å“We made very good progress in this regard and didn’t have any real problems with it, which is a major achievement given how big a component it is to introduce.
“It seemed to work quite well with the various mappings, and also the temperatures look under control so we can be quite confident in it.Ã¢â‚¬Â
LotusÃ¢â‚¬â„¢ Jarno Trulli was again the best of the newcomers as his team-mate Heikki Kovalainen was limited to just five laps after a technical problem with his car.
Virgin RacingÃ¢â‚¬â„¢s Timo Glock and Lucas di Grassi were over eight tenths off the pace of Trulli, while HispaniaÃ¢â‚¬â„¢s Bruno Senna and Sakon Yamamoto was 1.1 seconds slower than di Grassi.
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BIOGRAPHY: Victor Moses
BIOGRAPHY: Luke Shaw