Belgian GP: Fernando Alonso fastest in wet/dry first practice

Early rain over the Ardennes circuit meant the first and final sectors were saturated, in contrast to the middle split, where a dry line was rapidly established.

After the opening 15 minutes, in which McLaren's Jenson Button dominated, the mixed conditions effectively left the circuit too wet for slicks and too dry for intermediates, leading to a lull in activity.

The session finally sparked into life on the 45-minute mark as Mark Webber headed out on Pirelli's hard compound and immediately went fastest in sector two, even if his overall lap was some nine seconds off Button's early benchmark.

Webber's run, combined with several forecasts pointing to further showers in the closing minutes, inspired the entire the field to switch onto slicks and led to myriad changes at the top of the order.

Sergio Perez was the first man to displace team-mate Button with just over 30 minutes of the session to run, and on his next lap became the first man to dip below the 2m00s barrier.

Button reasserted himself immediately, only to be knocked off in turn by Nico Rosberg, Daniel Ricciardo and then Lewis Hamilton.

Ferrari was still yet to post a single flying effort as the session moved into the final half hour, but when it did emerge Alonso instantly hit the front, moving clear with a 1m57.1s.

There was still time for that to be usurped - firstly by Perez and then by Force India's Paul di Resta - but Alonso's next lap finally settled matters, earning top spot by just two hundredths of a second.

Di Resta's effort was enough for second, while his team-mate Adrian Sutil slipped into third late on, just ahead of Perez, Rosberg and Vettel.

Despite the conditions everyone managed to stay clear of the barriers, with incidents limited to a few trips down escape roads or run-off areas, particularly at La Source and the final chicane.

Pos  Driver               Team/Car              Time       Gap      Laps
 1.  Fernando Alonso      Ferrari               1m55.198s           11
 2.  Paul di Resta        Force India-Mercedes  1m55.224s  +0.026s  10
 3.  Adrian Sutil         Force India-Mercedes  1m55.373s  +0.175s  11
 4.  Sergio Perez         McLaren-Mercedes      1m55.518s  +0.320s  14
 5.  Nico Rosberg         Mercedes              1m55.614s  +0.416s  10
 6.  Sebastian Vettel     Red Bull-Renault      1m55.636s  +0.438s  14
 7.  Esteban Gutierrez    Sauber-Ferrari        1m55.954s  +0.756s  18
 8.  Nico Hulkenberg      Sauber-Ferrari        1m56.110s  +0.912s  11
 9.  Daniel Ricciardo     Toro Rosso-Ferrari    1m56.770s  +1.572s  14
10.  Valtteri Bottas      Williams-Renault      1m56.858s  +1.660s  18
11.  Felipe Massa         Ferrari               1m56.863s  +1.665s  10
12.  Pastor Maldonado     Williams-Renault      1m57.081s  +1.883s  14
13.  Jean-Eric Vergne     Toro Rosso-Ferrari    1m57.084s  +1.886s  17
14.  Jenson Button        McLaren-Mercedes      1m57.281s  +2.083s  14
15.  Lewis Hamilton       Mercedes              1m57.358s  +2.160s  10
16.  Heikki Kovalainen    Caterham-Renault      1m57.821s  +2.623s  16
17.  Giedo van der Garde  Caterham-Renault      1m57.887s  +2.689s  16
18.  Max Chilton          Marussia-Cosworth     1m58.600s  +3.402s  14
19.  Mark Webber          Red Bull-Renault      1m58.929s  +3.731s  12
20.  Jules Bianchi        Marussia-Cosworth     1m59.209s  +4.011s  12
21.  Kimi Raikkonen       Lotus-Renault         1m59.441s  +4.243s  11
22.  Romain Grosjean      Lotus-Renault         2m03.176s  +7.978s  15