Lotus Renault GP majority owner G?rard Lopez has revealed that he was 'surprised' Nick Heidfeld chose to turn up in the paddock at Spa-Francorchamps last weekend and that the German has vowed to fight the team's decision to drop him from its race line-up - describing it as 'an emotional reaction'.

Following a number of sniping remarks in the media about Heidfeld's performance as stand-in team leader at the Enstone-based outfit this year - from both Lopez and team principal Eric Boullier - speculation was rife that the 34-year-old's seat was far from safe, and on the eve of the Belgian Grand Prix, he was duly dropped in favour of reserve driver Bruno Senna, a man with just 18 prior F1 starts underneath his belt.

However, adamant that his contract is a binding one, Heidfeld travelled to Spa and has begun legal proceedings in a bid to reclaim the cockpit, with a hearing set to take place in London's High Court on 19 September - meaning that for the time being, Lotus Renault GP is able to confirm Senna only for the forthcoming Italian Grand Prix at Monza. Lopez admits the situation is a frustrating one.

"I was surprised," he told Tageblatt Luxembourg. "I would say it is an emotional reaction. His performance was not right, so we need to test other drivers. Nick has always been a good colleague, but we told him that we had not [had] from him what we had expected. He was always treated with respect and that will continue, because he is still a member of the team."

Heidfeld - who outscored team-mate Vitaly Petrov over the opening eleven races of the current campaign - remains convinced, however, that he has a solid case and will soon return to the grand prix grid.

"I cannot be very specific as something is pending," the 13-time podium-finisher told the BBC over the weekend. "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 were not 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."