Colo Colo were unable to make up ground on River Plate in the Copa Libertadores, playing out a 1-1 draw away to Alianza Lima on Thursday.
The Chilean side translated their early dominance into a goal in the 22nd minute albeit from a dead ball, when Leonardo Gil's corner was flicked on by Maximiliano Falcon, with an unmarked Lucero tapping in at the back post.
The visitors had a chance to double the margin only five minutes later when Pablo Miguez was called for a hand ball in the penalty area, but Lucero hooked his attempt and failed to hit the target.
Alianza made them pay straight out of the interval, equalising in the 46th minute. After some aerial tennis, Hernan Barcos deftly brought the ball down and played through Wilmer Aguirre, who fired past Brayan Cortes.
In what was ultimately a tight second half, Falcon had an opportunity to retake the lead for Colo Colo deep into stoppage time from another corner, but his unmarked header went agonisingly wide.
Although the draw leaves Los Albos only three points behind River Plate in Group C with seven points from four games, Fortaleza sit three points behind in third and can still relegate them to the Copa Sudamericana spot.
River Plate drop points in Brazil
The Colo Colo draw came after River Plate's shock 1-1 stalemate with Fortaleza at the Estadio Castelao.
After conceding only one goal over their opening three victories in Group C, Los Millonarios were down 1-0 in only the fourth minute, with Lucas Crispim setting up Silvio Romero.
Enzo Fernandez equalised 13 minutes later from the penalty spot after Tomas Pochettino was brought down, but despite good chances in the second half, River failed to capitalise and make it four victories from four.
Bragantino deny Velez a first Group C win
Velez Sarsfield's hopes of progressing to the knockout stage were dealt a blow after their 1-1 draw with RB Bragantino.
Veteran Lucas Pratto put El Fortin ahead in the 14th minute with a neat finish from an acute angle, and looked as though they were going to hold out for their first group-stage win in Sao Paulo.
With the goal, Pratto now has the highest active number of goals in the competition, scoring 28 times.
Jose Hurtado equalised for Bragantino in the 84th minute with his first-time volley, keeping them in second with five points and putting Estudiantes in box seat to progress from Group C.