It is a winner-takes-all clash in Belo Horizonte as the bottom two teams in Group C meet for a place in the Copa America quarter-finals.
Ecuador have lost both of their matches so far but know that a victory over Japan would see them through as one of the best third-placed teams.
A youthful Japanese squad, though, recovered from an opening match defeat against Chile to record a creditable 2-2 with Uruguay in a thrilling game last time out, and they will also progress with a victory.
Ecuador are favorites to triumph, due largely to the vast inexperience of the Japan squad. Before the tournament, 17 members of the Asian nation's group were uncapped and while they have shown talent, they undoubtedly lack big-match practice.
Ecuador have their captain and first-choice centre back Gabriel Achiller suspended after his red card against Chile in the previous game.
For Japan, new Real Madrid signing Takefusha Kubo could come back into the starting eleven after dropping to the bench against Uruguay.
Ecuador coach Hernan Gomez was furious after his side's defeat to Chile, with the manager refusing to give a post-match press conference - choosing instead to make a 30-second statement before leaving.
His team conceded two very basic goals against La Roja to add to the four that Uruguay had put past them in the first game, and in the seven matches Ecuador have played in 2019 their only clean sheet came in a friendly against Honduras.
Japan have showed some excellent attacking touches in both of their matches, and with both teams needing to win to progress, we should expect goals.
Tips and predictions
Over 2.75 goals on the Asian goal line is priced at 21/25 (1.84) and this looks like a strong angle for the game. This bet pays out in full if there are four or more goals in the game, while returning a half-win if there are only three goals.
These sides have played four matches in the tournament between them, with this selection paying out in full in three of those matches and paying out in half in the other.