Boca Juniors ended San Lorenzo's hopes of winning the 2008 Apertura with a 3-1 victory on Saturday that leaves Carlos Ischia's side in pole position for the title ahead of the final playoff game between them and Tigre on Tuesday.
San Lorenzo went into the match knowing that a win would secure them the championship, and had two golden opportunities to take the lead in the first 45 minutes - Nestor Silvera and Gonzalo Bergessio just unable to direct their respective headers on target.
Despite giving up some good chances to their opponents, it was Boca who enjoyed the lions share of first half possession, and it was therefore unsurprisingly when they went ahead in first half stoppage time.
Juan Roman Riquelme whipped in a corner from the left and Lucas Viatri pulled in front of his marker to head home, scoring his eighth goal of the Apertura in the process.
The early exchanges of the second half were conducted with a none too small measure of bite as San Lorenzo attempted to battle their way back into the match, with challenges flying in all across the pitch.
Miguel Angel Russo's side levelled the scores on the hour mark when Boca goalkeeper Javier Garcia allowed Santiago Solari's fairly tame effort to slip through his grasp and into the back of the net.
Boca were rocked by conceding and struggled to re-establish their control of the match in the fifteen or so minutes following the equaliser.
However, with the quality players that Boca have at their disposal, they always carry a goal threat, and it was a superb link-up between two of their most celebrated players that saw them retake the lead with just under quarter of an hour remaining.
Garcia launched a quick counter-attack by punting the ball high up field to Jesus Datolo, who brought the ball down and crossed towards Riquelme at the far post. As the ball dropped, Riquelme cushioned it perfectly into the path of on-rushing substitute Rodrigo Palacio, who finished calmly with his left foot to restore Boca's advantage.
San Lorenzo were clearly rattled and were soon down to ten men when Gaston Aguirre was shown his marching orders after pulling back Palacio for his second yellow of the match.
Bergessio was dismissed with three minutes remaining for dissent, and then San Lorenzo's ambitions of title success were killed once and for all as Cristian Chávez cut inside his marker and fired home from the edge of the area in stoppage time.
Boca will now been seen as favourites to take the title, as they can afford to lose 1-0 against Tigre on Tuesday and still be crowned champions for the 23rd time in their history.