How to join two tables on multiple foreign keys

i’ve been trying to join two tables for the world cup project , the best attempt i got is:

SELECT name FROM teams FULL JOIN games ON teams.team_id = games.winner_id AND teams.team_id = games.opponent_id WHERE round='Eighth-Final' GROUP BY name; 

but it seems broken ,like there’s no relation between the two tables anymore , however it works fine with only one foreign key.

@3xxxo try to use this interactive tutorial, and see if it can clarify some concept about querying multiple tables in SQL: SQLBolt - Learn SQL - SQL Lesson 6: Multi-table queries with JOINs