Host to first-placed Fluminense, Cruzeiro won 1-0 in the 29th round of the Brazilian championship on Sunday.
The win propelled Cruzeiro to first place of the tournament for the first time this year.
The winner came in the 14th minute. From the right side of the field, Montillo centered the ball to Wellington Paulista who reached the ball in time to head it past Rafael and into the back of the Fluminense net.
The win raised Cruzeiro's points to 54. In the 30th round of play, the team will travel to play Gremio on October 17.
Fluminense fell to second with 52 points. In the next round of play, the team will play host to cross-town rival Botafogo on October 17.