Gabriel Funes Mori scored with a second-half header to give River Plate a 1-0 victory over Arsenal on Sunday and a share of the lead in the Argentine Apertura tournament.
Funes Mori scored in the 75th minute to get River back to its winning ways after a loss and a draw in the team's previous two outings.
Both teams finished with 10 men after River's Roberto Pereyra and Arsenal's Pablo Aguilar were sent off just before the final whistle.
After the sixth round of fixtures, River, Estudiantes - which has played a game fewer - and Velez Sarsfield have 13 points, while Arsenal and San Lorenzo are a point behind.
Boca Juniors also claimed a much-needed win Sunday, with goals from Lucas Viatri, Martin Palermo and Juan Insaurralde earning a 3-1 win at Olimpo and easing the pressure on coach Claudio Borghi after a stuttering start to the season.
Elsewhere, defending champion Argentinos Juniors is still without a victory after losing 2-1 at home to Newell's Old Boys, while Independiente is also winless after being held to a scoreless draw at home against newly promoted Quilmes.
The match at the Monumental stadium between River and this season's surprise package Arsenal took most of the first half to warm up.
Funes Mori had the best chance of the opening period with a left-footed shot from the edge of the area that went wide in the 40th minute.
The striker from River's youth ranks had another chance with a 53rd-minute header that Arsenal goalkeeper Cristian Campestrini blocked.
It was a case of third time lucky for Funes Mori as he scored the decisive goal with a header from a corner to clinch victory and push River level with the tournament leaders.
The win was also important for River's relegation fears. In Argentina, relegation is decided at the end of each year by a table of average points per game from the previous three seasons.
River is perilously close to the bottom of this table after enduring two seasons of mediocre performances.
Meanwhile, Boca coach Claudio Borghi bought himself time with the win at Olimpo.
Boca had won just once in five games going into the match, but Viatri's opener from Palermo's pass in the 14th minute calmed nerves.
Olimpo got back in the game when Juan Manuel Cobo fired an equalizer three minutes later, but Boca reacted well in the second half and Palermo re-established the lead in the 62nd with a right-footed strike from the middle of the box.
Insaurralde scored Boca's third with a header in the 69th from another Palermo pass to make the game safe.
Earlier Sunday, defending champion Argentinos Juniors slumped to defeat despite taking the lead through a Gonzalo Vargas strike in the 17th minute at home against Newell's.
Gabriel Cichero equalized for Newell's in the 77th and Luis Miguel Rodriguez headed in the winner to complete the comeback in the 83rd.
Santiago Gentiletti was sent off in the final minute.
In Friday and Saturday results it was: Tigre 2, Gimnasia 0; Colon 1, All Boys 1; Huracan 2, Banfield 2; San Lorenzo 0, Velez 0; Lanus 1, Godoy Cruz 4; Estudiantes 2, Racing Club 0.