Fellow Brazilians Flamengo, who lifted South America's top club trophy in 1981, won 3-1 away to FC Caracas with two goals from Vagner Love, his first a penalty.
Corinthians lead Group One with four points from two matches. Flamengo, without the dropped Adriano and down to 10 men for 37 minutes after Toro was sent off for a second booking, lead Group Eight with a maximum six points.
Dentinho shot from outside the box on the left and his dipping effort found the top far corner of Paraguayan goalkeeper Aldo Bobadilla's net to cancel out Cesar Valoyes's goal for the Colombian champions.
Medellin went ahead in the 75th minute after left back Juan Valencia crossed low into the middle for Corinthians captain Chicao, who missed the ball but substitute Valoyes darted in to finish past keeper Felipe.
The goal came two minutes after an ineffectual, overweight Ronaldo had been substituted by Corinthians.
In a Group Six meeting between the champions of Argentina and Uruguay, Colombian teenager James Rodriguez scored twice to give Banfield a 2-2 draw away to Nacional at Montevideo's Centenario stadium.
Striker Gustavo Varela gave Nacional an early lead before 18-year-old midfielder Rodriguez struck twice, heading a 17th-minute equaliser and converting a penalty in the 35th, after he had been brought down, to put the Argentine side ahead.
Mario Regueiro pulled Nacional level just before half time when he tapped home the rebound after Uruguay central defender Sebastian Coates had headed a free-kick onto the bar.
Alianza Lima, the team that humiliated holders Estudiantes 4-1 three weeks ago, beat Juan Aurich 2-0 in an all-Peruvian match to lead Group Three with a maximum nine points. Alianza are five points ahead of the second-placed Argentine side.
Mexican champions Monterrey hung on for a 1-1 draw away to Once Caldas in Colombia in Group Two after having two players sent off in the second half.
