Australian 470 sailors Mat Belcher and Will Ryan have made an early statement ahead of the 2020 Olympics, winning the opening World Cup Series event at Games venue Enoshima, Japan.

The Rio Olympic silver medallists won five of the 11 races as they claimed the gold medal from Spanish duo Xammar Hernandez and Rodriguez Garcia with Japan's Kazuto Dio and Naoya Kimura third.

Belcher, 36, will be eyeing a second Olympic 470 gold medal next year, having triumphed with Malcolm Page at London 2012 before finishing runner up at Rio 2016 with Ryan.