Antofagasta have opened up the Chilean title race by stunning leaders Universidad Catolica 2-0, allowing O'Higgins to draw level at the top.
O'Higgins struck twice in the final 20 minutes to win 2-1 away to Union La Calera to join Catolica on 33 points at the top of the Primera Division, although the latter remain top of the league on goal difference.
In Antofagasta, Catolica suffered their second loss in three matches in all competitions with the hosts scoring twice after half-time through Kevin Harbottle and Jorge Javier Elizondo.
Catolica had won their past five league games but their slip-up on Saturday saw O'Higgins draw level with two rounds remaining in the Apertura season.
In La Calera, O'Higgins had to come from behind after Leandro Benegas had given the home side the lead in the 17th minute.
Pablo Calandria started O'Higgins' comeback in the 70th minute and Pedro Pablo Hernandez made it 2-1 with five minutes left.
Only Catolica or O'Higgins can win the Apertura title with the former facing 10th-placed Colo Colo and Union La Calera - who sit 16th - in the final two weeks, while the latter must play Union Espanola (fourth) and Rangers (15th).
Catolica also have eight goals worth of goal difference up their sleeve, should there be a tie on points.
Nublense claimed the win of the round, thumping Palestino 6-3, while Cobresal defeated Audax Italiano 3-1 and Everton won 2-1 away to Cobreloa.
In other results, Universidad Chile defeated Huachipato 1-0, Santiago Wanderers held Colo Colo to a scoreless draw, Union Espanola edged out Universidad Concepcion 1-0 and Rangers drew 0-0 with Deportes Iquique.