'This is no wonder-Sauber, it's only Pirelli.' Force India has attacked a claim that it is being out-classed by Sauber at the tail end of the 2013 Formula 1 season.LONDON, England - Force India has hit back at claims it is being out-classed by Sauber near the end of the 2013 Formula 1 season.The season began with Nico Hulkenberg thought to have made a grave error in moving from consistent Force India to Sauber but at the end of 2013 he has become a sensation and is reportedly being courted not only by Lotus but also by Ferrari and McLaren.Not only that but Esteban Gutierrez has earned his first points in F1 with the Sauber C31 at the 2013 Japanese GP.'SOMETHING IN HIM EXPLODED'Sauber team boss Monisha Kaltenborn said of Gutierrez' success: "Something in him exploded." Then she added that it might not be enough to safeguard the rookie's future - as Kamui Kobayashi knows well after his Suzuka podium in 2012.Kaltenborn added: "Individual results are not decisive when it comes to planning the future. We have some options but we're not going to name names."Kaltenborn, according to championship rival Force India's sporting director Otmar Szafnauer, knows well that the real sensation was not Gutierrez, or the formerly-struggling C31. The battle for sixth in the Constructors' championship is worth millions and crucial to teams such as Force India and Sauber.Szafnauer was angry that the decisive factor had been Pirelli: "This is no wonder-Sauber, it's only Pirelli. It is the whole explanation for the current situation."He was referring to how Pirelli's mid-season tyre specification switch badly hurt some teams, one of them Force India, while giving a big boost to others.