Atletico Rafaela failed to close the gap to the top of the Apertura standings as they fell to a 2-1 loss at San Martin San Juan.
Although the visitors took the lead through Dario Gandin after just 10 minutes, San Martin hit back in the second half with Lucas Landa (53) equalising and Raul Saavedra adding another six minutes from time - moments after coming off the bench.
Defeat leaves Atletico four points behind leaders Boca Juniors, who have a game in hand.
In the other match, Martin Rolle scored twice in three minutes to secure a 2-2 draw for Olimpo at home to Arsenal Sarandi.
Lisandro Lopez fired the visitors in front six minutes before the interval and Emilio Zelaya extended the lead two minutes into the second half.
But Rolle's goals in the 74th and 77th minutes earned Olimpo a share of the spoils, although they remain three places off the foot of the table.