Alonso is fastest in Belgian GP practice

(CNN) -- Fernando Alonso returned the fastest time in Friday's practice for Sunday's Belgian Grand Prix at Spa-Francorchamps.

The twice world champion, driving for Renault, has struggled to impose himself after his title victories in 2005 and 2006, but he emerged at the top of the standings after contending with rain and interruptions during the second session.

Felipe Massa, who has been in great form in recent weeks, had been quickest in the morning session but was relegated to second overall, still ahead of championship rivals Heikki Kovalainen and Lewis Hamilton, third and fourth respectively in their McLaren Mercedes.

Massa's Ferrari team-mate and defending world champion Kimi Raikkonen, winner of the last three Belgian Grands Prix, came fifth.

In the morning, In cold and damp conditions with specks of rain, Massa set a time of 1 minute, 47.284 seconds, beating Raikkonen by 0.339 seconds.

Hamilton had a time of 1:47.878, for an edge of 0.054 over Finland's Kovalainen and the British driver was quickest early on in the afternoon.

He lapped in 1:48.805 to beat Massa by 0.033 seconds. Drizzle then began to fall and conditions worsened in heavy rain.

Australian Mark Webber slid off the road at Rivage, his Red Bull's left-front corner finishing in the tire barriers.

Conditions remained difficult when the drivers returned to the track with just over half an hour remaining.

Raikkonen lost control and crashed into the barriers in his Ferrari.

Italian Giancarlo Fisichella in his Force India car then spun on the fluids left behind on the circuit by Raikkonen's car and hit the barriers as well.

Brazilian Nelson Piquet in the second Renault also crashed and damaged his car's rear wing.

As the track began to dry times improved. Kovalainen set a new session target, beating Hamilton by 0.015 seconds, but Alonso recorded 1:48.454 to finish on top.

"That was not a real guide to anything," he said after the session. "We cannot beat the others and the best we can hope for in qualifying is a good top ten place.

"For me now the motivation is not to win the races or the title but to do well, score points and help the team to beat Toyota. That is what keeps me going."