Lotus Renault GP boss Eric Boullier insists that money was not the reason his team dropped Nick Heidfeld in favour of Bruno Senna. To put it simply, the Frenchman claims that 'Quick Nick' didn't live up to his nickname.

"We have reviewed our performance, our level of motivation and a lot of things during the summer and I think I had to take a decision to show clearly some new direction," the Frenchman told reporters at Spa this afternoon.

As Heidfeld, still wearing his team gear, hovered in the paddock, the Frenchman continued: "Every weekend the media jump on me saying 'why is Vitaly faster than Nick? I was not very happy with the pure speed of Nick and his global performance as an experienced driver. That's it.

"Nick is a nice guy," he continued, "but I think something didn't work. His leadership didn't work in the team. And obviously when you are sometimes slower than Vitaly, and actually most of the time slower than Vitaly, it is difficult for him to push the team and to settle himself as a team leader. When you have a negative spiral starting, it's difficult to stop it. So I had to change something in the team to shake up and wake up everybody."

When asked by a German reporter whether money was really the issue, team owners Genii Capital having recently announced a $10bn joint venture in Brazil with the WWI Group, Boullier's face visibly reddened.

"It's always the same story coming out. It's amazing," he said. "Yes, it's true there is some relation with Brazil because Genii has signed a ten billion dollar deal...but nothing related with Bruno. Bruno is third driver and I guess it's logical that if we want to change our driver line-up that we promote our third driver. Full stop!"

Referring to the legal case, which is due to be heard next month, Boullier revealed that Heidfeld had already lost the first round. "They sought an injunction against Senna driving. They lost it because the judge recognised the contract was legal and not in breach and I can replace Nick.

"So now they go to the court because they are not happy and are suing me for something else maybe, I don't know," he continued.