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The Primera División B (First Division B: in English), also known as Primera División B Metropolitana or simply Primera B Metropolitana in order to distinguish it from the Primera División B Nacional, is the metropolitan tournament of the Paraguayan Tercera División. Only teams from the Gran Asunción metropolitan area and Central Department take part in this third division league. Teams from all other parts of Paraguay that are not part of the Gran Asunción area play the Primera División B Nacional tournament in order to get promoted to the Paraguayan Division Intermedia.
It is being played since 1939. Since that year, the number of teams, rules and names for the tournament have changed, but as of now it is called "Primera División C" (and no more "Primera de Ascenso"). For the 2021 season, 17 teams take part.
The champion of this league gains the right to participate in the Paraguayan División Intermedia and the second placed team plays a play-off game against the second placed team of the Primera División B Nacional (country third division tournament), to decide who will play in Paraguay's second division of football. The last one or two teams are relegated to the fourth division (called "Primera División C") for teams from Gran Asunción.