San Lorenzo failed to seal the Argentina Primera Division title after a 0-0 draw against Estudiantes on Sunday.
With Lanus draw 2-2 against Boca Juniors, San Lorenzo would have sealed top spot if they had claimed a home win.
The league leaders visit third-placed Velez Sarsfield on the final day as they aim for their first title since 2007.
Lanus missed the chance to draw level on points with San Lorenzo after twice giving away a lead at home to Boca.
Marcos Astina gave Lanus the ideal start with his goal midway through the first half as he placed an Oscar Benitez pass into the bottom corner.
Boca left-back Emanuel Insua set up the 51st-minute equaliser as Nicolas Blandi put away his cross.
Lanus midfielder Jorge Ortiz was sent off just moments later after a late challenge saw him pick up a second yellow card.
The hosts were lucky to get their third as Boca goalkeeper Agustin Orion tried to play out from defence and turned the ball over.
Jorge Pereyra crossed from the right and Benitez was on hand to poke into an empty net on 62 minutes.
Lanus' lead only lasted three minutes before Juan Sanchez Mino's low strike from inside the area beat Agustin Marchesin.
Matias Martinez was shown a straight red card for Lanus eight minutes before full-time after appearing to accidentally kick an opponent in the head.
Velez Sarsfield and Newell's Old Boys also remain in the title race.
A 2-0 win at Colon helped Velez move to within two points of top while Newell's Old Boys' poor form continued with a 3-1 loss at All Boys, but they are the same margin off first place.
Belgrano handed Arsenal a 4-1 thrashing, Tigre overcame Atletico Rafaela 3-1 and River Plate edged Argentinos Juniors 1-0.
Gimnasia La Plata claimed a thrilling 3-2 win over Quilmes, Godoy Cruz were beaten 1-0 by Olimpo while Rosario Central and Racing Club drew 1-1.
|25||P. Alvarado||64' 90'|
for L. Romagnoli 62'
for E. Kalinski 72'
for H. Villalba 82'
|Lampard welcomes ´perfect´ NYCFC challenge|
|Shamrock Rovers 3 Progres Niederkorn 0: Waters at the double|
|Gerrard keen to emulate ´hero´ Beckham at Galaxy|
|UEFA Champions League Review: Red Imps make history, TNS breeze through|
|Ameobi extends Newcastle deal and heads for Cardiff|
|U.S. women celebrate World Cup victory with LA rally|
|Atletico agree Vietto deal|
|Silva appointed Olympiacos head coach|
|Presidential candidates unsure of Turan´s Barca switch|
|Toure keen to bounce back from ´disappointing´ campaign|
|El Salvador v Canada: Floro targets Gold Cup learning curve|
|Juve complete Zaza swoop|
|Costa Rica v Jamaica: Borges confident Wanchope´s men are ready|
|Marseille snare Sarr|
|Italy coach Conte to stand trial in match-fixing case|
|Castan keen to repay Roma´s faith|
|Rami thrilled to reunite with ´best coach´ Emery at Sevilla|
|Lusitans v West Ham: Tomkins seeks to silence minnows|
|Kagawa shines as Dortmund hit six in Japan|
|Alonso tips Gerrard for Galaxy glory|
|Firmino seeks self-improvement with Liverpool|
|Buffon bids farewell to Pirlo|
|Sterling named Europe´s ´most valuable´ young player|
|Casillas´ agent reveals Porto offer|
|Southampton bring in Martina|
|Dundee United accept Celtic´s Ciftci bid|
|McArthur pens new Palace deal|
|Bartomeu rules out Barca move for Pogba this year|
|Spurs have to be better now - Bentaleb|
|Milner expects central role|
|Micronesia thrashed again, this time 46-0|
|Marchisio: I cannot be Pirlo´s heir|
|Inter aiming for Champions League return - Icardi|
|UEFA Europa League Preview: Brondby and Slovan to protect handsome leads|
|Bentaleb pens new long-term deal at Tottenham|
|Barca agree Turan deal|
|FIFA bans Mayne-Nicholls|
|United States v Honduras: Klinsmann demands improvement ahead of Gold Cup opener|
|CONCACAF institutes extensive reforms in wake of FIFA corruption scandal|
|Mauri completes Milan move|
|City sign Turkey striker|
|Women´s World Cup final draws huge US TV ratings|
|My first Chelsea team better than current crop - Drogba|
|Bertrand set for lay-off after knee surgery|
|New five-year Juve deal for Marchisio|
|Allegri extends Juve contract|
|Koeman reiterates Alderweireld interest|
|Valencia bag Bakkali|
|New York City FC complete Pirlo capture|
|Panama v Haiti: Collat ready to challenge the best of CONCACAF|
|UEFA Champions League Preview: Harrison eyes TNS progression|
|FIFA sanctions Yemen for fielding ineligible player|
|Toulouse rubbish Ben Yedder exit reports|
|Mourinho ´knows what he´s doing´ with Falcao signing|
|Watford shell out club-record fee for Capoue|
|Braafheid signs Lazio extension|
|Nani finalises Fenerbahce move|
|Liverpool confirm O´Driscoll appointment|
|Liverpool have to start better - Lucas|
|USA simply too good - Sasaki|
|Portland Timbers 1 San Jose Earthquakes 0: Jewsbury wins it in stoppage time|
|No move yet for Van Persie|
|Lloyd wins Golden Ball, Silver Boot awards|
|Mascherano: I never grabbed Banega|
|Dunga requested Brazil not appeal Neymar´s suspension|
|United States 5 Japan 2: Lloyd stars with hat-trick|
|Fiorentina deny Inter criticism|
|Nani relishing Fenerbahce opportunity|