As Mexico celebrated its World Cup-opening victory over South Africa on Thursday, a 2-year-old duck dressed in the national team’s colors, became an unlikely internet sensation and the tournament’s first unofficial mascot.

As World Cup fever sweeps Mexico, a pet duck dressed in a tiny Mexico football jersey has become an unlikely internet sensation

Julián Quiñones and Raúl Jiménez may have scored for Mexico, but Merlin the duck stole the show. The 2-year-old duck dressed in Mexico’s national colors became an internet…