Romanian Simona Halep poses with the trophy after beating Czech Republic’s Katerina Siniakova in Shenzhen on Saturday. PIC/AFP

World No.1 Simona Halep fired a warning to her Australian Open rivals on Saturday, beating Katerina Siniakova in three sets to win the Shenzhen Open. The Romanian saw off the reigning champion from the Czech Republic 6-1, 2-6, 6-0 in 72 rollercoaster minutes in rain-hit southern China. Halep, 26, is guaranteed top seeding for the Australian Open, the season's first Grand Slam, which begins in Melbourne on January 15. This was her 16th WTA title but the first since reaching the top of the world rankings in October. The match was delayed by five hours because of rain in Shenzhen and had to be moved indoors before play could begin.