Ok, it’s Wiki, but I assume it’s right.
** In the draws for the quarter-finals and semi-finals, there are no seedings, and teams from the same group or the same association can be drawn against each other. As the draws for the quarter-finals and semi-finals are held together before the quarter-finals are played, the identity of the quarter-final winners is not known at the time of the semi-final draw. A draw is also held to determine which semi-final winner is designated as the “home” team for the final (for administrative purposes as it is played at a neutral venue).*