Neither Boca Juniors nor River Plate broke into the Clausura's top two after the Superclasico between the two Buenos Aires teams ended 1-1.
Martin Palermo put Boca ahead 14 minutes into the second half but Marcelo Gallardo equalised with a free-kick nine minutes later as Velez Sarsfield stayed top of the table.
River trail six points behind Velez, who beat Arsenal 2-0 yesterday, while Boca are 10 points off top spot.
Boca were without star playmaker Juan Roman Riquelme, who failed to recover from a foot injury, but took the lead when Palermo's 30-yard piledriver screamed past Mario Daniel Vega in the 59th minute.
The advantage was shortlived, though, as Gallardo curled a free-kick past Roberto Abbondanzieri.
On Saturday, Velez Sarsfield scored at the end of each half to beat Arsenal 2-0 and retain top spot as the Argentine Clausura championship passed the halfway mark.
Uruguayan Rodrigo Lopez put Velez ahead when he collected Gaston Diaz's cross from the right and fired in from close range on the stroke of halftime.
Joaquin Larrivey had a penalty saved by Arsenal goalkeeper Cristian Campestrini in the 71st minute but Velez made sure of the points when Leandro Coronel capitalised on an incisive pass from Roberto Nanni in the 90th minute.
Velez, unbeaten after 10 games in the 19-match campaign, lead by one point from Colon, who beat Independiente 1-0 on Friday.
Racing Club eased their relegation worries by beating Banfield 1-0 to notch their third successive win.
Adrian Lucero scored the winner in the ninth minute after a one-two with Pablo Luguercio to lift Racing to seventh.
Racing, one of the country's most popular teams, are 16th out of 20 teams in the relegation standings which are decided over three seasons.
The bottom two go down while the 17th and 18th teams play off against second division sides.