River Plate

Argentina

Founded 1901·Champions (4 times) — most recently 2018

River Plate, Boca Juniors' fiercest rival, have won 4 Copa Libertadores titles (1986, 1996, 2015 and 2018). The most memorable came in 2018: after a 2-2 first leg at La Bombonera, the return leg at El Monumental was suspended after River fans attacked the Boca team bus, and the match was eventually replayed weeks later in Madrid — River won 3-1 at the Santiago Bernabéu in what became known as the "Madrid Superclásico." Founded in 1901, they did not qualify for the 2026 edition.