Four-time Asian Cup football champions Japan expect a tough opening match, without an injured Kaoru Mitoma, against Vietnam, coached by former Japan boss Philippe Troussier. “We’ve been analyzed by a coach who knows Japan,” Samurai Blue coach Hajime Moriyasu told a press conference Saturday in Doha, a day before the two sides meet in their Asian Cup Group D opener. “We are ready for a tough game and to come out winners in the end.” Moriyasu also revealed that Brighton winger Mitoma will miss the opening game due to a left ankle injury sustained in a Dec. 21 Premier League match against Crystal…