Check out the highlights from a wild opening round of the 2011 Rockstar Energy Drink MX Nationals, Australian Motocross Championship. Scotsman Billy Mackenzie was able to win a mud-filled Pro Open season opener, while earlier in the day in premium weather conditions it was Matt Moss (JDR Motorex KTM) and Luke Arbon (GYTR Rockstar Yamaha) who won the Pro Lites and Under 19s respectively.