Alonso leads practice 2

The world champion was followed by Renault's Giancarlo Fisichella, who vaulted from the midfield to second with a late lap just 0.287 seconds slower than Alonso's time.

Heikki Kovalainen matched his teammate's improvement to take third. He had been on course to pip Fisichella on his final lap before spinning at Turn 13.

Prior to the Renaults' laps, Alonso had been nearly eight tenths of a second clear of the field.

His McLaren teammate Lewis Hamilton was fastest initially - lapping in 1:22.301 after 10 minutes before improving to 1:22.188 on his next lap.

But 20 minutes later, Alonso emerged on the softer compound tyres and beat Hamilton's mark by 0.791 seconds. The champion's 1:21.397 lap would remain unbeaten throughout the final hour of Friday running.

The Ferraris ultimately reached fourth and sixth after a low-key start to the session. Felipe Massa had compromised two of his early laps with dramatic moments at Turn 10, but later pipped Hamilton to fourth, the British rookie having taken to the Turn 1 grass on his final run.

Toro Rosso's Scott Speed was the sensation of the afternoon. The American held second place early on, splitting the McLarens. He later went off the road briefly at Turn 8, but despite failing to improve his time, Speed would only drop down to 10th by the end of the session.

Other drivers exploring the limits of the circuit were Alex Wurz, who slithered sideways through the Turn 5 gravel, and Nick Heidfeld, who went over the grass at Turn 13.

Heidfeld ended the afternoon in eighth, behind Kimi Raikkonen and Nico Rosberg, and ahead of Mark Webber and Speed.

Pos  Driver        Team                    Time              Laps
 1.  Alonso        McLaren-Mercedes   (B)  1:21.397            33
 2.  Fisichella    Renault            (B)  1:21.684  + 0.287   39
 3.  Kovalainen    Renault            (B)  1:21.966  + 0.569   38
 4.  Massa         Ferrari            (B)  1:22.048  + 0.651   31
 5.  Hamilton      McLaren-Mercedes   (B)  1:22.188  + 0.791   37
 6.  Raikkonen     Ferrari            (B)  1:22.251  + 0.854   33
 7.  Rosberg       Williams-Toyota    (B)  1:22.415  + 1.018   29
 8.  Heidfeld      BMW Sauber         (B)  1:22.543  + 1.146   40
 9.  Webber        Red Bull-Renault   (B)  1:22.589  + 1.192   39
10.  Speed         Toro Rosso-Ferrari (B)  1:22.617  + 1.220   35
11.  Kubica        BMW Sauber         (B)  1:22.710  + 1.313   43
12.  Coulthard     Red Bull-Renault   (B)  1:22.719  + 1.322   30
13.  Button        Honda              (B)  1:22.808  + 1.411   39
14.  Barrichello   Honda              (B)  1:22.926  + 1.529   40
15.  Wurz          Williams-Toyota    (B)  1:22.950  + 1.553   30
16.  Liuzzi        Toro Rosso-Ferrari (B)  1:23.143  + 1.746   29
17.  R.Schumacher  Toyota             (B)  1:23.219  + 1.822   28
18.  Trulli        Toyota             (B)  1:23.307  + 1.910   42
19.  Sato          Super Aguri-Honda  (B)  1:23.493  + 2.096   40
20.  Davidson      Super Aguri-Honda  (B)  1:23.497  + 2.100   49
21.  Sutil         Spyker-Ferrari     (B)  1:23.609  + 2.212   33
22.  Albers        Spyker-Ferrari     (B)  1:23.736  + 2.339   30