[2] In his first and only season with the Middle Tennessee Blue Raiders in 2015–16, Zatar was named all-Conference USA (C-USA) second-team in singles and first-team in doubles.

[2] In late January he was named C-USA Men's Tennis Athlete of the Week for his performance in their loss against Vanderbilt, scoring the only singles victory for the Blue Raiders against the 25th-ranked team in the country.

[2] Zatar transferred to Georgia Gwinnett College for his sophomore season and won three straight NAIA team national championships with the Grizzlies from 2017 to 2019, compiling a record of 23–4 in singles matches and 47–5 in doubles play.

[12] Zatar won a bronze medal at the 2017 Bolivarian Games in Santa Marta, Colombia, teaming with Camila Giangreco Campiz in the mixed doubles event.

[14] He made his Davis Cup debut in 2015 in the Americas Zone Group III, defeating José Gilbert Gómez in straight sets in their first-round tie against Panama.

Although he and Juan Borna upset Santiago González and Miguel Ángel Reyes-Varela in the doubles rubber, Zatar lost both of his singles matches and Paraguay would lose the tie 1–4.