The Chelsea midfielder, 24, was dismissed in the 70th minute after his raised foot made contact with Castano’s face during a midfield challenge.
Castano, 23, received treatment on the pitch, while Fernandez was shown a straight red card.
The flashpoint was the most controversial moment in a match that ended 1–1 in Barranquilla on Tuesday (10.06.25) evening.
Argentina, who have already secured qualification for the 2026 World Cup, fell behind in the 24th minute of the match after a solo goal by 27-year-old Liverpool winger Luis Diaz.
The goal sparked an already intense contest into life, and tensions boiled over following Fernandez’s dismissal.
Lionel Messi, 37, appeared visibly frustrated following the incident and was seen exchanging words with Colombia captain James Rodriguez, 32.
Moments later, the Inter Miami forward was involved in another altercation, seemingly throwing an elbow toward Crystal Palace defender Daniel Munoz, 28.
Messi was substituted in the 78th minute and replaced by Exequiel Palacios, 25 – a move Argentina coach Lionel Scaloni later explained.
Speaking after the match, Scaloni was quoted by Argentine outlet TyC Sports saying: “Leo wasn’t going to come off, but he ended up coming off near the end. He told me it was better for him to come off, and so we decided to change him.
“The good thing we always showed, with 10 men and without Messi, is that we kept looking, not giving up on a ball. That makes us very satisfied.”
Palacios would go on to provide the assist for 23-year-old Thiago Almada’s equaliser, salvaging a point for the reigning world champions with less than ten minutes to go.
The result places Argentina ten points clear of second-placed Ecuador in the South American standings.
Their next qualifiers are scheduled for September — hosting Venezuela on the 9th before travelling to Ecuador on the 14th.
Fernandez will now serve a suspension, with his availability uncertain for Argentina’s upcoming fixtures.