Júnior Osmar Ignacio Alonso Mujica is a Paraguayan professional footballer who plays primarily as a defender, operating either as a centre-back or left-back. He is currently a member of Atlético Mineiro, competing in the Campeonato Brasileiro Série A, where he contributes his versatility, defensive awareness, and experience across the back line. At the international level, Alonso is also a regular member of the Paraguay national football team, representing his country in international competitions and qualifiers.