HO CHI MINH CITY (AFP) - Ri Kum-suk scored a hat-trick as a formidable North Korea booked their place in the Women's Asian Cup final on Thursday with a 3-0 trouncing of Australia. The Koreans, Asia's number one ranked team, will play either defending champions China or arch-rivals Japan in Sunday's decider as they go in search of a third title as the perfect warm-up for the Olympics in August. Tom Sermanni's side were on the back foot almost immediately when Ri fired a shot beyond goalkeeper Lydia Williams in the second minute to open the scoring. North Korea, who won the competition in 2001 and 2003, were looking dangerous and it was almost 2-0 six minutes later when Kim Yong-ae's pass nearly found Kim Kyong-hwa in the area before a defender cleared the danger. The Matildas, finalists two years ago, soaked up the pressure but didn't have a shot on target until midway through the half when Lisa De Vanna found some space but failed to trouble goalkeeper Jon Myong-hui. The Koreans extended their lead four minutes before the break when Ri Un-suk sent a dangerous pass across the face of goal, which Ri Kum-suk smashed into the roof of the net. Australia came out for the second half fired up and looked a far better side, but North Korea weathered the storm and Ri completed her hat-trick on the hour mark when she despatched a low shot through the legs of Williams. North Korea remain unbeaten in the tournament, including a morale-boosting 1-0 victory over China in the group stages.