The 2026-27 Primeira Liga season has only just begun, leaving traders with limited data to separate contenders for the most clean sheets. Mid-table and promoted sides such as Marítimo, Rio Ave, and Estrela da Amadora sit alongside established clubs like Sporting CP and Porto because defensive outcomes hinge on variables that remain fluid this early: goalkeeper form, back-line cohesion after summer transfers, and fixture difficulty. Historical records show wide swings in clean-sheet totals across a full campaign, and the current clustering around 45-49% reflects broad agreement that no side has yet established a sustained edge. Schedule congestion, potential injuries, and tactical adjustments in the coming weeks could quickly shift which teams grind out shutouts most effectively.