NAGOYA — South Korea shut down Hong Kong 13-0 on Tuesday as its pitchers combined for a perfect game in a rout that ended after seven innings on a mercy rule. Cho Hyeong-woo smoked a grand slam, and Roh Si-hwan launched a two-run home run in South Korea's second straight Group B win at Toyohashi Municipal Baseball Stadium in Toyohashi, some 85 kilometers southeast of the main host city, Nagoya. Starter Choi Min-seok and five other pitchers combined for a perfect game and struck out 12 batters. South Korea, made up of stars from the Korea Baseball Organization (KBO), is trying to win its fifth straight baseball gold medal. The quest began with a 5-0 win over Chinese Taipei on Monday, and South Korea will next face Thailand on Wednesday. The top two teams from each of the two groups will compete in the Super Round. The two best teams from the Super Round will clash in the gold medal game on Saturday in Toyohashi. Roh fired the opening salvo on Tuesday with a two-run bomb in the top of the first, and South Korea scored in each of the first three frames, with Cho's slam coming in the third