Ricardo Goulart's 53rd-minute strike was enough to see Cruzeiro condemn Santos to a third consecutive defeat at the Estadio Urbana Caldeira on Sunday.
The Brazil international played a neat one-two with strike partner Willian on the edge of the penalty area before firing the ball low and hard across Santos goalkeeper Aranha eight minutes into the second half.
League leaders Cruzeiro - unbeaten in six outings - have collected 70 points from 34 games, four more than nearest rival Sao Paulo, who have played an extra match.
Santos are in freefall, occupying ninth position following a run of five games without a win.
Brazilian striker Luis Fabiano scored his 100th Serie A goal for Sao Paulo in a 2-0 win at home to Palmeiras.
Luis Fabiano - in his third spell with the club - opened the scoring after 22 minutes at the Estadio Cicero Pompeu de Toledo, half-volleying Hudson's cross from the edge of the area.
Defender Rafael Toloi put the game beyond doubt with 11 minutes remaining, when he directed a ferocious volley into the roof of the net.
Sao Paulo, who played out a 1-1 draw with Internacional on Wednesday, are in the midst of a seven-game undefeated streak.
Gremio (+15) and Corinthians (+18) are level on 60 points with Internacional (+8), though the latter occupies third spot due their superior number of matches won.
Paulao's 79th-minute strike gave Internacional, who have played an extra game, a 1-0 win against Goias - their 18th triumph of the season.
Gremio notched their 17th victory of the campaign after goals from Dudu, Hernan Barcos and Ramiro inspired a 3-0 rout of cellar-dwelling Criciuma, who are seven points adrift of safety.
Renato Augusto scored six minutes from time as Corinthians overcame second-bottom Bahia 2-1 on the road for win number 16.
In other results, sixth-placed Atletico Mineiro earned a 1-1 draw at home to Figueirense.
Fluminense were 1-0 winners against third-bottom Botafogo and Vitoria climbed out of the drop zone with a 1-0 victory at Chapecoense, who dropped into the fourth and final relegation spot.
Flamengo downed relegation-threatened Coritiba 3-2, while Atletico PR lost 1-0 to Sport Recife.
