As mentioned in the lineup chapter, if one of your players gets injured, the substitute for that position will enter the field automatically. You can also set up preconditioned substitutions.
You can set up substitutions for a match in advance, either for making that master-mind tactical move or just to swap a tired player for a fresh one.
You can, for example, change a forward for an extra defender to secure your lead in a game, or swap a defender for a forward if you're down. You can also choose to change the individual player order for a player.
Adding a preconditioned substitution
To add a substitution you go to the "Subs/Orders" tab in the match order form. You pick the player you want to leave the field and the substitute who will enter. You then decide the conditions of the substitution.
You can set up the substitution to happen after a certain minute, and/or depending on the standings in the game by displaying the "advanced options". Here you can also add a condition for if one of your (or your opponent's) players gets a red card.
Adding a behavior change
You add behavior changes in the "Subs/Orders" tab too. Similar to adding a substitution you pick which player you want and then add the conditions for when you want him to change behavior.
You can add five player orders
You may add up to five different player orders (substitutions and behavior changes). But remember, the referee will not let you make more than three substitutions in a match.
Orders are carried out when the conditions are met
Player orders will be carried out in the match as soon as all the conditions set ahead of time are met. If the condition(s) isn't met, the order will not be carried out.
If you order a substitution in the 65th minute at any standing, the substitution will be carried out in the 65th minute. If you order a substitution in the 70th minute on the condition that you're in the lead, the substitution will be carried out the first time the condition is met after the 70th minute. So if you get into the lead in the 80th minute, your substitution will be carried out first then.
If you set up two orders for the 70th minute, one if you're in the lead and the other if you're in the lead by more than one, and you have a 3-0 lead when that time comes, both orders will be issued.
After the match you (but not your opponent) can see a list of all your player orders via a link on the star rating page, along with information of when they were issued or why they weren't issued.
You can't react to injuries
It's not possible to set up any condition for injuries. If one of your players gets injured during a match, the automatic system deals with it. This also means that an injury can mess up your substitution plans, just like in real life soccer.