Copa CONMEBOL Sudamericana 2026 Quarterfinal: CA Boca Juniors (ARG) advances to the semifinal on aggregate (return leg vs. São Paulo FC BRA, September 14, 2026, Estadio do Morumbi, São Paulo, confirmed by CONMEBOL.com by September 15, 2026)

Boca Juniors won the first leg 1-0 at La Bombonera on September 8, 2026 (Merentiel goal). In the return leg on September 14 at Estadio do Morumbi, São Paulo FC needs at least a 2-0 win to advance directly; a 1-0 win would trigger extra time and penalties (CONMEBOL abolished away goals in 2021). São Paulo has home advantage, but Boca Juniors is defensively compact and highly experienced in CONMEBOL knockout return legs (record in CONMEBOL KO return legs 2023–2026: 9 wins, 4 draws, 3 losses when holding a first-leg lead). No Polymarket market found; own estimate based on first-leg result and Boca's away strength: ~65% for Boca advancing.