Caterham's return to action after the summer break was rudely interrupted as Giedo van Garde suffered a heavy accident in Friday afternoon practice at Spa-Francorchamps.

The Dutchman, racing as close to his homeland as possible this weekend, was already lapping faster than team-mate Charles Pic when he lost control at Stavelot, sliding sideways into the tyre barrier and badly damaging his car.

"The weather had improved from the morning session, but the car didn't feel great on the first run," van der Garde reported, "We had a lot of oversteer on run one and not great traction, so we made a change and went out for run two on the medium tyres. The first run on those was ok but we weren't really able to get everything out of the softer rubber so there's definitely more to come from the softer rubber.

"On the long run on the mediums, the car felt pretty good, deg[radation] levels were okay but then, in turn 15, the back end got loose and I unfortunately made contact with the barrier, ending the session."

With Sebastian Vettel and Fernando Alonso suffering punctures in the same section of the circuit, they tyres have be listed as a possible cause, although van der Garde admitted that nothing was apparent immediately after the session.

"We're not sure why that happened yet, but we'll have a look at the data and investigate more tonight," he confirmed.

The Dutchman remained quickest of the Caterham drivers at the end of the day, out-pacing Pic by a tenth in the dry afternoon session as the Frenchman also reported handling problems.

"We went straight out in FP2 on the hard tyres and the car was okay, but the main issue on run one was mid-to exit oversteer," he explained, "We made a couple of mechanical changes for the second run, but still had the oversteer issue. With more changes, it had improved slightly for run three when we put the medium tyres on for the first time. The car was more calm on mid-to-exit, but we found we had some issues on entry into the corners so, for the long run, we put on a bit more front wing and it did feel like we made some progress.

"We still need to make more improvements to the stability of the car on entry into the corners, but we can look at that more tonight, as well as keeping an eye on the weather forecast for tomorrow - and even more for Sunday."

The regular pairing was once again joined by Heikki Kovalainen, who took over Pic's car for the morning session. With steady drizzle affecting the track surface, however, the Finn was mired at the bottom of the combined timesheets, despite having edged van der Garde earlier in the day.

"It felt good to be back in the car and I'm pleased to see how it's developed since I last drove it in Barcelona," Kovalainen reported, "The whole package feels better balanced and, generally, it's a good overall improvement behind the wheel.

"There's a few things I could tell right away that are better - in general, the ride has improved, there's much less pitching and the front, in particular, feels stronger. Against that, the braking stability doesn't feel great today, but that's something that can be worked on pretty simply in FP2. Overall I'm pleased I had more time in the car and can continue to help the team progress."

Kovalainen's presence will no doubt raise questions over the future for both van der Garde and Pic, although neither appeared too concerned by the speculation.

"Next year is still far away," the Dutchman insisted, "I still want to focus on the next [few] races, do well, maximise myself. I think the new tyres are helping me a little bit, with my style of driving, so then we'll see where it ends up.

"I've been working really hard. Of course, it's not easy for rookies to come in. I think [Marussia's] Jules [Bianchi] was a little bit better than me at the beginning, but it went better and better and you see a good direction going, especially the last race, [where] it was going really well. I'm happy with the team, happy with the performance and we keep on pushing like this."

"My job is to try to get 100 per cent out of my car every weekend," Pic, who was reprimanded by the Spa stewards for rejoining the track directly in front of Sebastian Vettel early in FP2, echoed, "So I will be focused on this for the next races and will let my management do the rest."