Spa-francorchamps: Nick Heidfeld plans to take High Court action in London against Renault in a bid to force the British-based team to honour his contract as their lead racing driver.
Heidfeld was ousted from his seat in the team on Wednesday by Brazilian Bruno Senna, nephew of the late legendary former champion Ayrton Senna.
An interim agreement has given Senna an opportunity to race for Renault at both this weekend's Belgian Grand Prix and the Italian Grand Prix next month.
But Heidfeld is not prepared to take the slight lying down and intends to fight back and regain his seat.
In a statement on Friday, the normally mild-mannered racing driver said: "I was surprised by the team's intention to replace me and regret that things have developed this way.
"I just wanted to be in the cockpit to get the best result for the team and me. I still have a clear contract and I want to drive."
Speaking to BBC Sport later in the day, he said he felt confident about his case.
"I cannot be very specific as something is pending," he said.
"It's disappointing not to be here as a race driver but that is the situation at the moment and I have to live with that.
"If we would not be confident that we have a case here, we wouldn't follow it up and yes, I believe this is the situation.
"I have a good feeling inside the team. People like me. I've worked with the team for over a year and always enjoyed working with them."
His manager Andre Theuerzeit said he was hopeful that the 34-year-old German would be back in a Renault cockpit in time to race in Singapore on September 25.
He said he intended to force the team to honour the driver's contract before the London High Court next month.
"I am disappointed that the team is allowed to let another driver take Nick's seat for the next weekends," said Theuerzeit.
"However, I certainly am confident that we will be able to enforce a fair solution for Nick in the further proceedings. We all hope that Nick will be back in the cockpit in Singapore."
Heidfeld's legal representative Dr Stefan Seitz said: "The interlocutory decision of the court does not infringe on the fact that Nick has a valid contract to be one of the two main drivers of the team.
"This position is disputed by the team for apparently purely financial reasons. We do not intend to rest before Nick's legal position has been fully restored."
In Friday's opening practice sessions for Sunday's Belgian Grand Prix, Senna ended the day in 17th place, having run 20 laps in the rain while team-mate Russian Vitaly Petrov was 24th and last after suffering with a steering problem.