River Plate beat their old rivals Boca Juniors at La Bombonera for the first time in a decade, moving up to fourth in the table.
The 2-1 victory as reignited the title race in Argentina, but confounded Boca's disappointing season which has now has hit a new low.
Heavy rain in Buenos Aires before the game turned the pitch at La Bombonera into a giant lake, but the grounds crew were able to do enough to get the pitch slow, but playable.
The first half had plenty of chances for both teams but River Plate players Cristian Ledesma and Teofilo Gutierrez could not make the most of their opportunities, while Juan Manuel Martinez was denied for the hosts.
Hosts go behind
The deadlock was finally broken in the 58th minute when Manuel Lanzini expertly latched onto a through ball from Gutierrez and chipped over the on rushing Boca keeper to put River Plate ahead.
Ten minutes later, Boca responded through a superbly directed Juan Roman Riquelme free kick from 20 yards out that goal keeper Barovero could not lay a finger on to draw his team level.
Boca surprisingly took Riquelme off, seemingly content with a draw, and were made to pay for it in the 86th minute.
Their marking was terrible on a corner into the head of Ramiro Funes Mori, who rose up and directed the ball into the top corner to send the away fans wild.
Source: Al Jazeera