June 19 (Reuters) - Seven-times Formula One champion Lewis Hamilton dispelled the "myth" surrounding a chassis swap with Mercedes team mate Valtteri Bottas after qualifying for Sunday"s French Grand Prix. Hamilton and Bottas had swapped chassis for this weekend"s race at the Paul Ricard circuit as part of a planned rotation, Mercedes said in the build-up. As a result, the Briton has been driving the chassis used by Bottas in the last four races, including a nightmare last round in Baku, while the Finn has the chassis that has carried Hamilton to three wins from six races. Mercedes said both chassis were identical, but the swap, coinciding with an upswing in form for Bottas and greater struggles for Hamilton, has led to speculation and conspiracy theories. "I saw you coming up with some myth so I was happy to be able to prove you wrong," Hamilton told Sky Sports F1 commentator and former racer Paul di Resta in the post-qualifying interviews. "The quality of our engineers" work, (our) cars are exactly the same." Hamilton qualified second on Saturday, behind Red Bull pole-sitter Max Verstappen but ahead of Bottas in third. The fired-up Finn, who headed into the weekend with speculation surrounding his Mercedes future, had led Hamilton through all three practice sessions. Hamilton admitted to struggling but said that had more to do with getting the car in the optimum operating window. "As you can see today I managed to do a great job with the same car," he said after beating Bottas in qualifying. "So it’s no different. "We’re just in general struggling with getting everything from the tyres and getting the car in the right window." Bottas agreed, saying: "I think it"s more in the head. "You think some chassis is better, some not, so I don’t think there’s much difference."