The 2017 New Zealand Motocross Championships is quickly building into another classic top of the table Kiwi versus Aussie battle.

With the four-round champs kicking off at Pleasant Point near Timaru a little over a week ago, there's been little time for riders and fans to catch their breath with round two set for Rotorua this Sunday.

Mount Maunganui's Cody Cooper (Honda) battled hard to keep Australian visitor Dean Ferris (Yamaha) at bay at Timaru, and after a brutal day of close racing the pair were separated at the top of the premier MX1 class standings by just five points.

Not too far behind them was Mount Maunganui motocross coach Rhys Carter, the Kawasaki man finishing inside the top three is all three MX1 races at Timaru, to sensationally edge out Australian professionals Todd Waters (Honda), Jesse Dobson (Honda) and Luke Styke (KTM).

Cooper and Ferris also respectively finished first and second overall in the MX1 class last season, Ferris eventually missing out on the title by just two points, and that outcome could be traced back to the spectacular crash he suffered at the corresponding event at Rotorua last year.

Now well aware of the pitfalls on the hilly Rotorua circuit, it is unlikely Ferris will make the same mistake this time around.

In the MX2 (250cc) class it was a similar case of the defending champion leading the way, although Takaka's national MX2 No.1 Hamish Harwood (KTM) was even more comprehensive in winning his class at Timaru.

With three wins from three starts, the South Island rider, who is now based in Takapuna, was emphatic in demonstrating that he wants to keep the MX2 crown.

Christchurch teenager Dylan Walsh (Yamaha) has just returned from two seasons of racing in the United States and he was expected to keep Harwood honest at Timaru.

He certainly did that but, with his finishing third in the first race at Timaru, behind Reporoa's Hadleigh Knight (Husqvarna), and then twice crossing the line as runner-up, he trails Harwood by 11 points at the start of this weekend.

Third best overall in this class is Knight, the 20-year-old just six points behind Walsh.

In a remarkable display of talent, strength and stamina, apprentice builder Harwood is also racing a 300cc KTM in the MX1 class and there he is currently positioned seventh overall, just six points behind fulltime professional racer Styke.

The 125cc class is developing into a two-rider fight, with Taihape's Hayden Smith (KTM) and Karaka's Kurtis Lilly (Husqvarna) scrapping over the race wins at Timaru.

This battle is the tightest of the series, with just three points to separate leader Smith from runner-up man Lilly, while Nelson's Hayden Wilkinson (Yamaha) is third overall, 14 points further back.

The competition next heads to Palmerston North for round three on March 12, with the fourth and final round set for Taupo on March 25.