Ferrer, the two-time defending champion in Buenos Aires, is hoping to win his 21st ATP tournament.
Fognini, who won the ATP event last week in Chile, advanced Friday by defeating Pablo Andujar of Spain 6-4, 6-3.
Robredo advanced against Robin Haase of the Netherlands. Robredo won the first set 6-1, and Haase retired with an injury after falling behind 2-0 in the second set.
No. 1 Rafael Nadal pulled out of the tournament with a back injury but will play next week in the Rio Open in Rio de Janeiro.