The 27-year-old Antúnez joined Chivas USA during preseason of the 2013 season. Antunez was born in Santa Ana, California and grew up in Southern California before moving to Texas in high school.
The All-State high school midfielder played college soccer at Lon Morris College in Texas and University of Hartford in Connecticut. He was drafted in the 2008 MLS Supplemental Draft by the Colorado Rapids. Before joining Chivas USA, Antunez played for the USL Rochester Rhinos, Estudiantes Tecos and FC Inter Turku (Finland).