ZURICH, OCT 15: Top seed Martina Hingis (Switzerland) dismissed the attentions of an obsessive fan to reach the semi-finals of the Swisscom Challenge Tennis tournament here.The World No 1 fought off a 2-5 first set deficit to see off American qualifier Corina Morariu 7-5 6-2 last evening.Tournament officials confirmed security for Hingis had been stepped up after a 42-year-old Yugoslavian man admitted sending faxes to the Swiss player in Filderstadt, Germany, last week. The fan was in the audience as Hingis dropped only four points in five games to take first set, before enjoying another run of four games to win the match.Results (Pre-quarter-finals): 2-Venus Williams (US) bt Irina Spirlea (Rom) 6-3 6-2, 3-Mary Pierce (Fra) bt Chanda Rubin (US) 6-1 6-2Ivanisevic outVIENNA: Austria's Stefan Koubek advanced to the quarter-finals of the Ca Trophy last evening, beating Croatia's Goran Ivanisevic 6-7 (3-7), 6-2, 6-4.Pre-quarter-finals: 6-Richard Krajicek (Netherlands) bt Magnus Larsson (Swe) 6-4, 6-2, 7-Nicolas Kiefer (Ger) bt Juergen Melzer (Aut) 6-4, 6-0, Karol Kucera (Slo) bt 8-Nicolas Lapentti (Ecu) 6-2, 6-3, Sebastien Grosjean (Fra) bt Marat Safin (Rus) 6-4, 4-6, 7-6 (7-5)Hewitt moves upSINGAPORE: Fourth seed Lleyton Hewitt took advantage of his opportunities today to reach the semi-finals of the Singapore Heineken Open for the first time at the expense of Holland's Jon Van Lottum 6-4, 6-2.In another quarter-final, Mikael Tillstrom (Swe) beat Ivan Ljubicic (Croatia) 7-6 (7-4), 4-6, 6-3
