I always talk about the strategy with the yellow cards in SF rounds... in your case is complicted... because you have to win and a troll result can appear in your case.
In a case like your, the 1st is the 1st and the 1s is win the round, so, by my viewpoint in your situation:
1- or I put all players under the field and when I see that the result is sure, then I do subs' to protect. Then if I loose 1 it doesnt matter.
2- or I put some of ma players with yellow card, maybe I select as subs' some defender, if I have another with guarantee to play the same position. Maybe in this case or, I protect my better player, and he play only if needed, or, the better player play till I have the result.

LOL... you played so, hope all went ok.