SYDNEY - Bulgarian qualifier Tsvetana Pironkova's fairytale run at the Sydney International ended with her first WTA title when she stunned world number nine Angelique Kerber 6-4, 6-4 in the final on Friday. Pironkova had already beaten world number six Petra Kvitova and number seven Sara Errani in the seven matches it took her to get the final and rode a second set fightback from her German opponent to claim the victory."Mum and Dad, we have a trophy," the 26-year-old former Wimbledon semi-finalist beamed after her triumph. Juan Martin Del Potro earlier underlined his status as a dark horse for next week's Australian Open by hammering Dmitry Tursunov to set up a men's final against Bernard Tomic.Men's world number three David Ferrer was also the victim of a shock, however, when his bid for a fifth Auckland Open title was ended in the semi-finals by a 6-4, 7-6, (7-4) loss to Taiwan's Lu Yen-hsun. At the Kooyong Classic exhibition, Richard Gasquet dealt another plot twist to the injury-plagued Kooyong Classic Friday when the Frenchman withdrew from the final, citing fatigue, just days before the start of the Australian Open. Gasquet had been due to take on Czech star Tomas Berdych in Saturday's showdown after a semi-final victory against countryman Gilles Simon who retired during the second set.But Gasquet's withdrawal means Berdych will play what largely amounts to an exhibition match against Japan's Kei Nishikori who he earlier knocked out of the eight-man Australian Open warm-up. Gasquet progressed to the final two when Simon rolled his ankle and was forced to retire on the eve of the first Grand Slam of the season, which starts in Melbourne on Monday. Simon turned his right ankle on the first point of the second game of the second set after Gasquet won the first set in 51 minutes, handing the match to his countryman 7-6 (7/4), 1-0.Tall Argentine Del Potro, who will be seeded fifth in Melbourne, hit nine aces as he brushed aside Tursunov 6-4 6-2 in just over an hour to reach his seventh final in the last 12 months. Two of those were at Masters events in Shanghai and Indian Wells, an indication for some that Del Potro might be returning to the level of form he reached to win the 2009 U.S. Open title before a wrist injury nearly ended his career.In Saturday's final, the 25-year-old will meet Australian defending champion Tomic, who made heavy work of coming from behind to beat Ukrainian qualifier Sergiy Stakhovsky 6-7 (4-7), 7-5, 6-3. Del Potro is seeded to meet world number one Rafa Nadal in the quarter-finals of the year's first grand slam, while Tomic was revealed as the Spanish 13-times grand slam champion's opponent in the opening round in Friday's draw.World number five Del Potro is one of only six active male grand slam champions and the Argentine believes he might soon be challenging Nadal, Roger Federer, Novak Djokovic and Andy Murray again. "I think I'm getting closer to the top four guys," he said on court. "They are still playing such great tennis but if I am fit, I will try to be dangerous for them."Sam Stosur, another former U.S. Open champion, went down 6-3, 6-2 in the semi-finals of the Hobart International to Klara Zakopalova, who she will meet again in the first round at Melbourne Park. Zakopalova will first face Spain's Garbine Muguruza Blanco in the Hobart final after she thrashed compatriot Estrella Cabeza Candela 6-0, 6-1 in the second semi-final. At the Auckland Open, world number 62 Lu stunned Ferrer in two sets to bring the Spaniard's 14-match, three-year winning streak at the tournament to an end. Lu will face big-serving American John Isner, who came from behind to beat Spain's Roberto Bautista 3-6, 7-6 (7-2), 6-4, in his first ATP final on Saturday.