The match was played in an ugly atmosphere following Defensor's 2-0 win the previous week in Montevideo and tempers boiled over just before halftime when a brawl erupted, leading to red cards for Cruzeiro's Nilton and Defensor's Matias Malvino.
Cruzeiro went ahead in the fifth minute of first-half stoppage time with a majestic free kick by Everton Ribeiro and former AS Roma, Real Madrid and Sevilla striker Julio Baptista added a second just after the hour.
Felipe Gedoz pulled one back for the Uruguayans three minutes later and they stunned the Mineirao stadium when Emilio Zeballos equalised in the third minute of stoppage time.
The result left Cruzeiro third in Group Five with four points from four games, three behind second-placed Defensor and five adrift of group leaders Universidad de Chile.
Thursday's other four matches all finished in home wins.
Atletico Paranaense easily disposed of Universitario 3-0 in Group One in a game featuring two extraordinary blunders.
Paranaense forward Ederson missed an open goal in the first half but got on the scoresheet late in the game with the help of Universitario goalkeeper Jose Cevallos, who made a complete hash of a back pass.
The win left the Brazilians level at the top with Velez Sarsfield on nine points while the Peruvians are bottom after four straight defeats.
Lanus beat Deportivo Cali 2-0 in Group Three after Jorge Pereyra and Maximiliano Velazquez scored in the first five minutes, their first win of the competition.
Cerro Porteno's 2-1 win over O'Higgins in the same group featured three goals in the opening ten minutes as the Paraguayans went top with seven points, one ahead of Cali.
Daniel Guiza, a member of Spain's Euro 2008 winning squad, and former Bayern Munich midfielder Julio dos Santos, from a penalty, put Cerro 2-0 ahead in Asuncion and Pablo Calandria replied for the Chilean champions with another spot kick.
San Lorenzo's dismal campaign continued with a 1-0 defeat away to Union Espanola, leaving the Argentines bottom of Group Two with four points.
The visitors had Mauro Cetto sent off in the 53rd minute for a dangerous lunge at an opponent before Gustavo Canales headed the winner in the 67th minute.
- Sports & Recreation
- Julio Baptista
- Real Madrid
- Everton Ribeiro