Do you have to go on the career mode to get achievements: Night Round 3? (Xbox 360)?

I do not understand, Im confused. On the main menu I went on "Play now", created an account and chose Mohammed Ali as my boxer and chose my opponent as some feather weight boxer...I chose an arena and it had Burger King logos everywhere so I presumed I would get the first achievement if I won this match (The first achievement:"Win The BK Invitational Fight").-By the way I had the game set to easy mode. I did win this match but got no gamerscore from it...Why???