Emiliano Papa grabbed a second-half winner as Velez Sarsfield beat Olimpo 2-1 to go second in the Clausura.
Ricardo Alvarez gave visitors Velez a first-minute lead but a penalty from Martin Rolle in the 39th minute brought Olimpo back on level terms.
However Papa netted in the 51st minute to allow Velez to jump six places and reach 14 points from seven matches, leapfrogging Olimpo in the process.
Racing Club had two men sent off as they lost 2-1 at home against Tigre, with Lucas Licht dismissed in the 43rd minute and substitute Luis Farina following him five minutes from the end.
Mariano Pernia put Tigre ahead after 23 minutes, and Denis Stracqualursi doubled the lead in the 51st minute. The ten men of Racing Club pulled a goal back through Claudio Yacob in the 77th minute, but the late red card for Farina scuppered their hopes of an equaliser.
Struggling Newell's Old Boys came from two goals down to draw 2-2 with Arsenal Sarandi. The visitors surged 2-0 ahead when Luciano Leguizamon scored after 26 minutes and Mauro Obolo followed suit three minutes later.
Juan Cobelli pulled one goal back in the first minute of the second half, and Sergio Almiron equalised in the 53rd minute. Newell's had Mauricio Sperdutti dismissed 11 minutes from time.
The remaining match, between All Boys and Lanus, finished goalless.