5 sets
Explanation:
Matches are played best of five sets. The first four sets are played to 25 points, with the final set being played to 15 points. A team must win a set by two points. There is no ceiling, so a set continues until one of the teams gains a two-point advantage. Previously, all sets were to 15 points, with the first four sets having a ceiling of 17 and the final set requiring at least a two-point winning advantage.
