For the most part, seeds in tennis are determined by the players' rankings as of the week the event's officials create the draw sheet for the event, which is usually written a week or two in advance of the event. However, some events reserve the right to modify the seedings, in order to place lower-ranked players in the place of a higher-ranked player, usually to make the draw more interesting to the spectators and sponsors, or to support a local player. This is true for amateur, college, and professional events.