Liga TDP is the fourth level professional division of Mexican football. Formerly called Tercera División de México (1967–2017). It has 225 teams divided into 17 groups. In the 2009–10 season, the format of the tournament has been reorganized to a home and away format, which all teams will play in their respective group. The 17 groups consist of teams which are eligible to play in the liguilla de ascenso for three promotion spots, teams which are affiliated with teams in the Liga MX, Liga de Expansión MX and Liga Premier, which are not eligible for promotion but will play that who the better filial team in a sixteen team filial final phase tournament for the entire season.