no, you have to have 14 players min. in the team, so you can not sell more players if you have 14. The "automatic defeat" happen when of the 14 players you don't have 11 to start playing the match. so if you have 10 players ok +5 injuried you have an auto defeat for 3-0.

Too of course you have to count the red cards, that is = -1 player too.