While his cousin began his career at Nacional, O'Neil came through at their Uruguayan Clásico rivals Peñarol,[1] the club he supports.
[2] Four days later he played the full length of a 2–1 win over Colón of Argentina in the group stage of the Copa Libertadores, also at the Estadio Campeón del Siglo.
He was not chosen by manager Kily González during an eventually successful fight against relegation, and missed several games due to involvement with the Uruguay under-23 team.
[10] Halfway through the year he returned to his country on a free transfer, signing for Sud América in the Uruguayan Segunda División.
In the fifth-place playoff against Colombia, he came on as a late substitute and scored the first attempt as his country won in a penalty shootout after a goalless draw.