Kamada strikes inside four minutes
Japan were ahead almost before Tunisia had touched the ball. Keito Nakamura's low cross from the left split the defence and Daichi Kamada flicked it home with the inside of his left foot after just three and a half minutes. This is the fastest goal a Japanese player has ever scored at a World Cup. Ueda doubled the lead in the 31st minute, controlling Ko Itakura's long pass before drilling a finish into the far corner.
The game was put to bed after the break. Ito, starting in place of the injured Takefusa Kubo, ran onto Ueda's lofted pass and swept the ball beyond goalkeeper Aymen Dahmen on 69 minutes. Ueda then headed in a Kaishu Sano cross seven minutes from time to complete the rout. Japan did not concede a single shot on target all evening.
Moriyasu credits preparation, Renard stays defiant
Japan head coach Hajime Moriyasu pointed to the work done before kick-off. "We prepared well for what we wanted to do and played aggressively," he said. He also thanked the travelling support, noting that "many Japanese supporters came here to Monterrey, sang the national anthem with us and cheered us on loudly."
For Tunisia, the defeat confirmed elimination in Hervé Renard's first match in charge. Renard was appointed on 16 June after a 5-1 opening loss to Sweden and the dismissal of Sabri Lamouchi. "We still have a third game to play, we are at a World Cup and must remain focused," Renard said. "We must be professionals to the very end."
Ueda struck his first two World Cup goals yet barely celebrated. The 27-year-old, the Eredivisie's leading scorer with 25 goals for Feyenoord last season, has explained that restraint before. "It's my style, my modesty," he said. "When I've scored, I hear the fans and their joy. I let that sink in. I also think of my wife who has always supported me."
A historic night in numbers
The win arrived in the 1,000th match in World Cup history. Japan became the first team from Asia to score four goals in a single World Cup game, and Ueda the first Japan player to score twice in one. It was also their first four-goal display at a World Cup.
The victory ended a long second-match drought for Japan, who had not won their second group game at an overseas World Cup across their previous six attempts. Their only earlier second-game win came in 2002, when they co-hosted the tournament.
Ueda finished with two goals and an assist. Kamada has now scored in back-to-back World Cup matches.
Japan need a point against Sweden
Japan sit on four points after a 2-2 draw with the Netherlands and the win over Tunisia. They are level with the Netherlands, who lead the group on goals scored after a 5-1 win over Sweden. Sweden have three points; Tunisia are out with none.
Japan face Sweden on Thursday in their final group game and need only a point to secure a place in the Round of 32. The Netherlands play Tunisia in the other Group F fixture.