BUENOS AIRES (Reuters) - Newell's Old Boys' chances of retaining the Argentine league title hung by a thread after a crushing 3-1 defeat at All Boys on Saturday.
San Lorenzo can snatch the title with a match to spare if they beat Estudiantes at their Nuevo Gasometro ground on Sunday and Lanus drop points at home to Boca Juniors.
The Saints lead the 'Inicial' championship with 31 points from 17 matches while Newell's are joint second with Velez Sarsfield, both on 30 from 18, after Velez won 2-0 at bottom team Colon.
Lanus have 29 points from 17 matches and Arsenal 29 from 18 after their 4-1 home defeat by Belgrano. Boca have 27.
All Boys, fresh from a 2-0 upset victory over Boca at La Bombonera last weekend, overran Newell's in the first half on their tight Islas Malvinas pitch and had the ball in the net three times in the opening 10 minutes.
Their first effort was ruled offside but Maxi Nunez put the home side ahead in the ninth minute and Chilean midfielder Gonzalo Espinoza scored a brilliant second a minute later curling a shot across goal and into the top far corner.
Right back Hernan Grana hit the third in the 35th as Newell's, winners of last seasons 'Final' championship under coach Gerardo Martino before he departed for Barcelona, went a seventh match without a victory.
Midfielder Pablo Perez pulled one back in the 65th.
"Let's hope it is still possible, but it's never happened to me to let so many chances slip and be champions. I'm destroyed but conscious we did all we could," Newell's former Argentina defender Gabriel Heinze told TyC Sports.
"Alfredo (Berti) is a hard working person ... we got this far because of him," Heinze said referring to Martino's successor. "We players are responsible," he added of the team's loss of form.
All Boys, celebrating their centenary, are a modest club in the Buenos Aires 'barrio' of Floresta who have spent a mere 12 seasons altogether in the top flight.
They are fighting to avoid relegation, which is based on team's average points over a season, but on Sunday's form their future looks bright.
San Lorenzo host Estudiantes at 2030 GMT and Lanus, who qualified in midweek to meet Brazil's Ponte Preta in the final of the Copa Sudamericana, kick off 45 minutes later against Boca.
(Editing by Greg Stutchbury)