BUENOS AIRES, Dec 10 (Reuters) - Boca Juniors, needing only a draw to clinch the Argentine championship, crashed to a shock 2-1 home defeat by Lanus on Sunday to set up a title playoff against Estudiantes.
On an evening of high drama, Estudiantes scored two late goals to beat Arsenal and 2-0 finish level with Boca at the top of the Apertura championship on 44 points from 18 games. Goal difference is not used to decide the title.
Boca, who also lost 1-0 at Belgrano last week when they needed only one point to clinch a third successive title, appeared to be on their way when Martin Palermo fired them in front from a 31st-minute penalty.
Goals from Claudio Graf and Rodrigo Archubi, however, gave Lanus an unlikely win in front of a stunned crowd at the Bombonera, including Diego Maradona watching from his VIP box.
Even then, the title appeared to be Boca's until Estudiantes, playing with the same never-say-die approach shown by coach Diego Simeone during his playing days, struck twice in the last five minutes to sink Arsenal.
Boca coach Ricardo La Volpe, who said Friday that he would resign if his side did not win the championship, watched in disbelief from the dugout.
The former Mexico coach took charge halfway through the campaign after Alfio Basile was appointed coach of Argentina.
Lanus, sixth with 31 points, gave an early warning of what was to come when Maxi Velasquez fired over from an excellent position.
Boca took the lead when Agustin Pelleteri handled and Palermo converted the penalty for his 10th goal of the competition.
Lanus equalised one minute before halftime when Lautaro Acosta broke down the right and crossed to the far post where Graf headed his ninth goal of the tournament.
In the 58th minute, there was an even greater shock when Archurbi, despite being slightly off-balance, scored with a low shot from the edge of the penalty area.
Palermo and Daniel Diaz both missed chances to equalise as Boca pressed forward desperately.
There was even worse news for Boca at Estudiantes.
Arsenal held on until the 86th minute when former Lazio and Manchester United midfielder Juan Sebastian Veron crossed and defender Agustin Alayes scored with a header which went in off the crossbar.
Mariano Pavone added the second in stoppage-time.
In other matches, River Plate finished third after a 1-1 draw at Velez Sarsfield.
Teenage striker Gonzalo Higuain, who last month turned down a call-up from France where he was born, scored with a spectacular strike early in the second half.
Lucas Castroman grabbed a late equaliser for Velez, who finished seventh with 30 points.
Former Costa Rica striker Paulo Wanchope scored his fifth goal of the competition to help Rosario Central finish on a winning note by beating Colon 3-0.