At the 2004 Summer Olympics in Athens, Nunez competed again in the same programs as her first stint. She posted FINA B-standard entry times of 1:13.25 (100 m breaststroke) and 2:34.10 (200 m breaststroke) from the Pan American Games in Santo Domingo, Dominican Republic. In the 100 m breaststroke, Nunez challenged seven other swimmers on the second heat, including 13-year-old Yip Tsz Wa of Hong Kong. She blasted a Cuban record of 1:12.14 to earn a second spot and twenty-seventh overall behind winner Inna Kapishina of Belarus by a 1.48-second margin. In her second event, 200 m breaststroke, Nunez placed twenty-eighth on the morning's preliminaries. Swimming in the same heat as her first, she rounded out a field of six swimmers to last place by three tenths of a second (0.30) behind Mexico's Adriana Marmolejo, outside her entry time of 2:36.40.