Newell's Old Boys spoilt San Lorenzo's Easter Sunday with a 1-0 win in the Saints' first Argentine championship home match since Pope Francis became their most famous fan.
Argentina winger Maxi Rodriguez did the damage with a superb goal in the 37th minute of a match at the Nuevo Gasometro that had begun in a party atmosphere.
Striker Ignacio Scocco was inside the Newell's half when he received a clearance from his goalkeeper and he threaded a fine low ball that split the defence for Rodriguez to run onto and steer home under Saints keeper Pablo Migliore.
Newell's went joint top on 16 points from seven matches in the "Final" championship standings, although Lanus can pull three points clear again if they beat Quilmes at home on Monday. San Lorenzo are in mid-table with nine points.
The Saints lined up for a team photo before kickoff in front of a large red and blue banner adorned with a picture of Jorge Bergoglio, the Argentine pope who has been a club member since his childhood.
The Saints had enjoyed a victory, 1-0 away to Colon in Santa Fe, in their first match after the papal annoitment but league action was interrupted last weekend for World Cup qualifiers.
Martin Palermo's Godoy Cruz are third with 14 points after they came from behind to beat San Martin 3-2 away in an exciting Andean "clasico" in San Juan.
Ten-man Boca Juniors held Independiente 1-1 in Sunday's big derby at the Libertadores de America stadium in the capital between two of Argentina's top clubs.
Boca had defender Cristian Cellay sent off in the 11th minute, then had goalkeeper Agustin Orion to thank for saving a 17th minute penalty from midfielder "Rolfi" Montenegro before striker Santiago Silva gave them the lead in the 38th.
Independiente, beset by relegation worries, equalised through Paraguayan defender Claudio Morel Rodriguez in the 63rd minute.
River Plate are fourth with 13 points after being held 0-0 at home on Saturday by title holders Velez Sarsfield, winners of the "Inicial" championship in the first half of the season.
Diego Cagna resigned as coach of Estudiantes after their 1-0 home loss to Racing Club in La Plata on Saturday. Estudiantes have picked up only three points from three draws.