Bruno Senna says he must perform consistently at a high level to build his F1 career

The Brazilian, who will start seventh on the grid for the Belgian Grand Prix, was called upon to replace Nick Heidfeld by team boss Eric Boullier for this race and the next one at Monza in Italy next month. And Senna says he knows he needs to perform consistently at this level now or risk losing the momentum that his strong initial form has generated.

"It was obviously a good start but these were very tricky conditions and some drivers that are faster in dry conditions," he said after qualifying. "I seemed to be very fast in these conditions fortunately, but there is still lots to prove.

"I want to be consistently good and if I can be that then I can make my career."

Senna, who has sat on the sidelines for much of 2011, having struggled at the back of the grid with HRT last season, added that getting into Q3 on his first attempt with Renault was an unexpected boost to his debut with the team.

"It's a lot better [than I had hoped for], but I did not know what to expect to be honest," he said. "This morning after being P9 in the wet and it was straightforward conditions in terms of everybody going out and doing laps - I was confident that in the wet I could do a good job.

"When the conditions were changing for qualifying and the forecast was going maybe for dry I got a bit more nervous - because of course I hadn't... I knew that yesterday it was very, very difficult for me in the drier conditions.

"But just getting to Q3 was a massive victory for me. I knew that I could push, especially on the last few laps because I had not much to lose to be honest in that situation. I didn't want to make a mistake, go off and crash, so in that sense I wasn't pushing 100%. But I was pushing where I knew I could push and get away with outbraking myself a little bit.

"And I think where I other people mistakes I didn't and the result is there."

Asked whether he thought this performance would silence those who suggested he was only in the seat because he brought money to the team, Senna replied: "The only way to answer those things is to drive well. I think that I have done a good job today so it takes some of the question marks away. But every time I drive the car I have to continue doing that until I'm a professional Formula 1 driver.

"Eric [Boullier] was with me in GP2 and he knows that I can be competitive so he gave me a great vote of confidence when he put me in the car," he added. "First when he selected me as third driver this year and then when he put me in the car this weekend and the last one in Hungary and I hope that I can make him proud.

"Because these opportunities aren't showing up everywhere all the time so I am hanging on to it very much."