If a player leaves your club due to retirement or sale, then you would normally have to put a replacement player into your line-up yourself.
But, the system can help you out temporarily, until you get the chance to adjust your line-up yourself.
In this case, the system will put in a replacement player from your reserves. You must, of course, already have set up reserves corresponding to the pitch placement of the player who left your club. If you haven't, then the system will not perform any substitution. Read the Reserves section for information about which rows of reserves correspond to which pitch placements.
Notice: The system will only put in replacements for sold or retired players until you have had a chance to look over your line-up.
As soon as you have opened and saved your tactic after a player has left your club, the line-up will be considered as approved by you, even if there are still players missing. Therefore, the system will stop putting in replacements.