Nico Rosberg gives worrying assessment about Ferrari's ongoing team battle with Mercedes

Reigning Formula One world champion Nico Rosberg believes Mercedes have the Constructors' championship sewn up and it is unlikely that Ferrari will catch the Silver Arrows team.

The German believes his former team have superior resources when it comes to developing the car during the course of the season compared to their Italian counterparts despite the latter closing the gap during the winter and building an aerodynamically efficient car.

Ferrari are constantly challenging Mercedes this year after their domination for the last three seasons. The Maranello-based team have won four races thus far, just two shy of Mercedes' tally and they are 39 points behind in the team battle.

Moreover, Sebastian Vettel has taken all of Ferrari's victories thus far and leads Lewis Hamilton in the Drivers' Championship by 14 points with nine races remaining in 2017. The German led Ferrari's second one-two finish of the season at Hungary, and closed the gap on the Brackley-based outfit in the Constructors' Championship.

However, Rosberg is not convinced and the 2016 F1 champion believes Mercedes will run away with the title this season as most of the races — apart from the street circuit in Singapore — before the campaign concludes in November suits the German owned team. The former Williams driver admitted that he was surprised with Ferrari's dominance in Hungary, but believes the next outing in Belgium at the iconic Spa-Francorchamps will favour the Mercedes team.

"Ferrari have really done a great job over the winter," Rosberg told SPORTBILD, as quoted by ESPN. "But now it will be a development race. I find it hard to believe that Ferrari can keep up. After Silverstone I had already thought: That's it now."

"I was surprised that Ferrari in Hungary hadn't fallen back again. Spa would have to be a full-on the Mercedes-track. Ferrari is unlikely to have a chance," the German added.