Olimpo and Banfield both scored narrow successes to take over at the top of Argentina's Clausura. Olimpo had Ezequiel Maggiolo to thank for his goal, on the hour, which gave them victory over visitors All Boys - who had Eduardo Dominguez sent off in the closing stages of the match.
Banfield left it late to seal a 2-1 success at Tigre, with substitute Facundo Ferreira netting a 90th-minute winner. El Taladro had led through Cristian Garcia's 23rd-minute goal but Diego Morales levelled ten minutes after half-time for Tigre.
Both teams move on to ten points, one more than previous leaders Estudiantes and Racing Club.
