Japanese master Daiya Seto became the first swimmer ever to claim six straight world titles in the same event at a short-course championships Saturday as Lithuania's Ruta Meilutyte smashed the women's 50-meter breaststroke record.

Two further world records tumbled on day five in Melbourne — in the men's and women's mixed 4x50-meter relays.

Seto, 28, swam a storming breaststroke leg to claim the lead then powered home with his unbeatable freestyle to win the 400-meter medley in 3 minutes, 55.75 seconds.