The opening night of the Copa Libertadores group stage is always electric, but Fluminense's 0-0 draw away to Deportivo La Guaira in Venezuela was overshadowed by a bizarre refereeing blunder that left everyone scratching their heads.

The flashpoint came in the 68th minute. Fluminense forward Rodrigo Castillo was charging forward on a dangerous break, only to be brought down by a cynical foul from La Guaira defender Osio. The problem? Osio was already on a yellow card, and this challenge was a clear second booking, warranting a red card and an early shower.

In a moment of pure confusion, referee José Javier Burgos reached for his pocket—but booked the wrong man. The yellow card was mistakenly shown to Osio's teammate, Rivero, who was nearby but not the offender. The error went uncorrected, allowing Osio to remain on the pitch and keeping La Guaira at full strength.

After the final whistle, Fluminense's frustration was palpable. Striker John Kennedy didn't mince words, arguing the first foul on Osio was worthy of a straight red. "It was a challenge above the ankle," he fumed. Full-back Samuel Xavier piled on, criticizing the referee's tolerance for time-wasting and questioning the minimal stoppage time added.

The controversial non-call wasn't the only grievance; Fluminense also felt aggrieved by a denied penalty shout after a ball struck Osio's arm in the box. It was a night where decisions, or the lack thereof, defined the match.

While the result leaves the defending champions second in Group C with a single point, their focus now sharply turns to a colossal domestic clash: a Rio derby against Flamengo at the Maracanã this Saturday. The quest for Libertadores redemption continues on April 15th. For now, the memory of a confusing night in Venezuela will linger as a stark reminder of football's fine margins.