Daria Kasatkina has won her first tournament since becoming an Australian citizen.Kasatkina defeated Germany's Tamara Korpatsch 2-6, 6-3, 7-5 in a marathon Catalonia Open final in Vic, Spain.The clay-court tournament is a second-tier WTA 125 event.WTA 125 events are considered the equivalent of men's ATP Challenger tournaments.But for Kasatkina, the triumph came after she slumped to her lowest world ranking for 11 years.She entered the tournament at 75 on the WTA standings, a far cry from her career-best ranking of eight, which she achieved in 2022."Can't describe how happy I am to lift this trophy after a long time of struggle," Kasatkina wrote on Instagram."Thanks everyone for your support."Russia-born Kasatkina switched allegiance to Australia last year.She became an Australian citizen in January.AAP