MONTE CARLO, Monaco - A shadow is hanging over Nico Rosberg's Monaco Grand Prix win now that Red Bull and Ferrari have launched a pre-race protest.Mercedes' rivals allege the German squad conducted an illegal three-day test with Pirelli at Barcelona, just after the 2013 Spanish Grand Prix.F1 POLITICSRed Bull's team principal Christian Horner said: "What annoys me is that it was so underhand.”The FIA summoned all of the parties to hearings in the Monaco stewards' room immediately after the race. It appears Pirelli's right to conduct a mid-season test, and the strict in-season testing ban, have collided in a cauldron of typical Formula 1 politics.Mercedes team boss Ross Brawn insists he checked with the FIA prior to the test, "and they were happy".Horner, however, insists: "The team has run a current car with current drivers and current tyres. That's a clear breach of the sporting regulations."A Ferrari spokesman agreed that while Pirelli was allowed to test, it had to be with a two-year-old car. "The fundamental aspect is the year of the car," he said, "because if you use a current car it should be allegedly a breach". Stay with Wheels24 for the 2013 Formula 1 season – fresh reports every day.