Fernando Alonso gave struggling Ferrari a timely boost with the fastest time in Friday's rainy first practice session at the Belgian Grand Prix.

The two-time former champion is without a win in five races and has disappointed in qualifying all season, failing to even place on the front row. But the Spaniard clocked a best lap of 1 minute, 55.198 seconds on the Spa track, putting him .026 ahead of British driver Paul di Resta and .175 clear of Adrian Sutil.

They set their best times when the track was at its driest.

Three-time defending champion Sebastian Vettel was sixth fastest for Red Bull.

Many drivers stayed in their garages when the rain started to fall again late in the session. Lewis Hamilton, who won the last race in Hungary, was 15th behind former McLaren teammate Jenson Button.

The second practice is later Friday.

Conditions are often wet in Spa, and the 7.004-kilometer (4.352-mile) circuit is the longest on the calendar and the most demanding along with Monaco.

Because of the circuit's size, different microclimates mean it can be raining on one part of the track and sunny at another. Corners such as the steeply climbing Eau Rouge and Blanchimont push drivers and tires to the absolute limit.

On Friday morning, it was dry at the bottom end of the circuit but damp near the finish line.

Button, who won at Spa last year, is one of the best drivers in wet conditions and has targeted a podium place on Sunday. The McLaren driver has not finished higher than fifth this season, but was unlucky not to do better than seventh at the Hungarian GP last month.

On Thursday, Alonso played down a rift within Ferrari by saying that a recent public rebuke from president Luca Di Montezemolo was all down to a misunderstanding.

The day after the Hungarian GP, where he finished a disappointing fifth, Alonso was asked what he would like as a 32nd birthday present and responded with an acerbic "somebody else's car" after drifting down from second to third place in the overall standings behind leader Vettel and Kimi Raikkonen.

Ferrari scolded him on its website, with Di Montezemolo stating he had "tweaked the ear" of Alonso.

Alonso says it was all a big misunderstanding and that he is fully focused on racing for Ferrari.