The game *usually* tries to place friends together. If you invited each other into the game without having started it prior to that, it should work. Can you see your friend's (the one not in your league) fixtures? If they are there, he is on the same server as you and there is still possibility for you to be in same CL, Cup, or League. If you cannot see them, he is *not* on your server, and you will only be able to play friendlies with him.