Sponsors are an important source of cash in Tennis Manager. When you contract with one, it provides a signing bonus to you. Then, it commits itself to increase your tournament earnings by a fixed percentage, with an additional bonus if you win the tournament.

Some sponsors are only interested in high visibility players. To unlock new sponsors, you have to upgrade your Business and Media Center to hire a better agent, able to convince better sponsors.

Some of my sponsor earnings are divided by 2 and displayed in red!
While you don’t have any agent, you cannot sign new sponsoring contracts and all your existing contracts have their earnings lowered. Don't forget to have an agent by your side all the time so your don't miss your sponsor earnings!