Chile's experienced Copa America team proved too good for Japan's young squad.
The two-time defending champions opened their Copa America campaign with a 4-0 win over the Asian guests on Monday, with Eduardo Vargas scoring a pair of goals to become Chile's all-time leading scorer in the South American competition.
Erick Pulgar and Alexis Sanchez also scored for the titleholders, which are trying to become the first nation to win three straight Copa titles since Argentina in the late 1940s.
Vargas scored twice in the second half to reach 12 goals with Chile in the tournament, two more than Enrique Hormazabal.
The victory moved Chile to the top of Group C along with Uruguay, which opened with a 4-0 win over Ecuador on Sunday.
"Chile has players who are very experienced, who know each other very well," Chile coach Reinaldo Rueda said. "The challenge today was to avoid a bad debut. We were humble and entered with our feet on the ground. We were playing against a team that was very competitive in all sectors."
Japan, playing as a Copa America guest for the second time, brought to Brazil a young squad focused on the Olympic tournament at home next year. The Japanese youngsters struggled against the veteran Chilean squad which was in control from the start at the Morumbi Stadium.
Chile won the last two editions of the Copa America, beating Argentina in penalty shootouts in the final both in 2015 and 2016. Argentina is the only team to have won three consecutive South American titles, from 1945-47.
Boosted by most of the 23,253 fans at the Morumbi, Chile created most of the significant chances.
After Pulgar headed in a corner-kick cross by Charles Aranguiz in the 41st minute, Vargas added to the lead with a shot from outside the area in the 54th after a pass by Mauricio Isla.
Sanchez found the net with a header in the 82nd, and Vargas closed the scoring about a minute later with a long lob shot over goalkeeper Keisuke Osako as he charged from his net.
It was a good opening match for Sanchez after a difficult season with Manchester United.
"I was coming off a difficult month-and-a-half," said the 30-year-old Sanchez, who injured his ankle late in the season. "I struggled in the first 45 minutes, I felt tired, but I improved in the second half."
Rueda, debuting with Chile in an official tournament, has been gradually revamping the squad since he took over in 2018. Among the veterans back from the team's recent triumphs were Vargas, Sanchez and Arturo Vidal, who also had a good opener.
Japan last played in the Copa America in 1999, when it was eliminated in the group stage. Among the youngsters in Brazil was Takefusa Kubo, the 18-year-old who has joined Real Madrid's "B'' team for next season.
He played from the start and was a threat for Japan in attack. He got an ovation from the crowd at the Morumbi after getting past a defender with a ball through his legs about 10 minutes into the match. He nearly scored after a nifty move past a defender inside the area in the 65th, but his shot hit the outside of the net.
Japan had a few good chances to get on the board toward the end of the game but couldn't capitalize on them.
Qatar, host of the 2022 World Cup, is the other guest nation in this year's tournament. It drew 2-2 with Paraguay in its Group B opener on Sunday.