BARCELONA (AFP) - Australian Casey Stoner powered his Honda to victory in the Moto GP category of the Catalunya GP, the fifth race of the motorcycling world championship Sunday. Stoner finished ahead of Spaniard Jorge Lorenzo and American Ben Spies, both on a Yamaha, at the Montmelo circuit to claim his third victory from five starts after winning in Qatar and France. Lorenzo's second place kept the Spaniard in the lead of the overall standings with a seven-point cushion on Stoner. Honda rider Marco Simoncelli, who had to employ bodyguards after receiving threats from fans angered by his role in a collision which left Spanish rival Dani Pedrosa injured last week in France, started from pole position. However the Italian never got the start he hoped for, with Lorenzo pushing past second-placed Stoner to take the lead from the outset. His advantage was to be all too brief, lasting only one lap as Stoner -- currently considered the fastest man in the category -- took command in convincing fashion. Lorenzo battled to keep pace with his Australian rival in the opening laps but was given a reminder of the task ahead when Stoner clocked a fastest time on lap five to push the Spaniard a significant three tenths of a second further back. Spies meanwhile was having his best race of the season, the American managing to hold on to third place from the first lap to the last. The white flags indicating the presence of humid and potentially dangerous sections on the circuit came out at the halfway mark, however they failed to disrupt proceedings as the track steadily dried. In the Moto2 category Germany's Stefan Bradl, riding a Kalex, claimed victory ahead of Spaniards Marc Marquez, of Suter, and Aleix Espargaro, of Pons Kalex. Bradl made his intentions clear early on, taking the lead and never looking back as he forged towards a third victory in five races which reinforced his lead in the standings. Spaniard Nicolas Terol, riding an Aprilia, claimed victory in the 125cc category. Terol had originally finished second behind Johann Zarco however the Frenchman was later penalised 20 seconds and demoted to sixth place for making a dangerous manoeuvre. Another Spaniard, Maverick Vinales, finished second with Germany's Jonas Folger in third -- handing Aprilia a podium sweep at the Montmelo circuit.