Bruno Senna counting on wet qualifying for Renault debut at Spa

The Brazilian has been drafted in to replace Nick Heidfeld after Renault grew disappointed with the German, who had been hired at the start of the season as a substitute for the seriously injured Robert Kubica.

Rain affected all bar 15 minutes of today's two practice sessions at Spa, leaving Senna short of experience in the car in normal conditions.

"I'm sure that if it's dry it's going to be a real big challenge in qualifying," he said. "Today I had very tough dry running with some traffic and some KERS issues, so I couldn't really focus on pushing the car.

"Of course I had to be very careful about not putting a wheel on the wet kerb or the wet line and going off again, as that would have set me back massively. I don't think I was driving anywhere near 100 per cent. So if it is dry qualifying, it's going to be tough.

"But of course in a race situation it's very different. With the fuel load, everybody's going to be a bit more careful. I know that every run will be important again in the race but it's a learning curve and there's no better way than driving around to learn.

"Nobody has done very many laps on the dry tyres, so I think if the race is dry it becomes a bit more of a gamble. For sure if qualifying tomorrow is wet and stable, it will be better for me. If qualifying is wet and the race is dry, we're going to have a nice big challenge."

Senna crashed in the morning after putting a wheel on the white marker line at Turn 9, but said he had been delighted by the way Renault rallied behind him following the incident.

"When I made my mistake this morning, instead of beating me up, they gave me great support," he said. "They told me to clear my head and do a great job in the afternoon and they'd all be behind me. I think I have great support behind me and that's a very nice feeling."

He also dismissed rumours that he had only been given the race seat for sponsorship reasons.

"If you look at the team right now, there are no new stickers on the car or on myself," Senna said. "That's not why I'm in the car. The team trust that I can do a good job and are probably looking to the future. Of course there's a great commercial potential for the team with myself in it and hopefully they can exploit that. But I'm confident that the team is not giving me the opportunity just because of that, but because they believe that I can do the job."

At present Senna is only guaranteed the Renault race seat for Spa and Monza as Heidfeld is mounting a legal challenge to the team's decision to drop him. Senna denied that potentially only having two chances to impress put him under a lot of pressure.

"To be honest I'm not thinking about that. The pressure would be the same if I was guaranteed to do the next three years," he insisted. "What I want to do is sit in the car and deliver. My [self-imposed] pressure is bigger than the pressure than comes from outside and that's how I work. I've been able to deal with this pressure before and I can deal with it now. I just need to sit in the car and drive a little bit."

The wet weather - and some steering issues for Vitaly Petrov - meant there was little chance to directly compare the two Renault drivers' pace, although Senna acknowledged that he had probably not been on a pair with his team-mate today.

"Vitaly unfortunately had some issues with his car today in the afternoon so the comparison wasn't really meaningful. He didn't do dry running," said Senna. "We could look at some things and it was alright, but there are still loads of things to do. There was no way I could jump in the car and switch it on like this."