MANILA-BASED Gerald and Jennifer Rosales turned the opening round of the Hong Kong Open Junior Championship into a family affair at Discovery Bay Golf Club yesterday. Philippine junior champion Gerald, 16, fired an even-par 72 over the Lantau Island Club's Diamond-Ruby layout to open up a commanding six-shot lead in Class A. His 14-year-old sister, the Asia-Pacific girls champion in her age group, returned a 75 to head the female category in the 36-hole tournament, sponsored by MacGregor. ''I'm pleased with how I played. I didn't make many mistakes,'' said Gerald, a five-handicapper, who like Jennifer, plays out of the Aguinaldo Golf Club in Quezon City. Striking the ball with confidence, Gerald set the tone for his round with a pitching wedge to within two metres at the opening hole. He sank the putt for a birdie-three and never looked back. His round included further birdies at the par-three eighth and the par-five 12th. The only blemishes on his card were a three-putt bogey at the fifth and dropped shots at the ninth and 13th, where he missed the greens with his approach shots. In joint-second place going into today's final round are Singapore's Lam Chih Bing and Himmat Singh, of India. Lam, a member of Singapore's silver medal-winning team at this year's Southeast Asia Games, paid the price for an over-cautious approach. Using his driver just three times, Lam failed to record a single birdie on his way to a 78. Taking a three-iron for safety off the tee at the 417-metre, par-five fourth hole backfired badly for Lam. He pushed his drive into thick rough from where he needed two to escape. He hit his fourth on to the green and three-putted for a destructive double-bogey seven. Singapore's Alvin Khoo, from the Warren Golf Club, is the leading male in Class B for players aged between 12 and 14. Khoo returned a 78 and has a five-shot buffer over the Thai duo of Ekapak Nirapathpongporn and Sira Srisakorn. Hong Kong's Roderick Staunton is on course to retain his title in Class C for players aged 11 and under. Playing from the red tees, Staunton recorded a 76 to build up a 10-stroke lead over Thailand's Kavipong Meanpetch.