Having dropped points for the first time this season in the league last time out with a 1-1 draw against Benfica, Sporting Lisbon returned to winning ways thanks to efforts from Colombian Fredy Montero and Andre Martins in the space of nine minutes.
Montero's goal was his sixth in four league games this term and leaves Sporting two points adrift of Porto.
Olhanense's two-game unbeaten ended as a result, but they will look to get back to winning ways against Gil Vicente next week.
A brace from Alan, including one from the penalty spot, put them ahead and then Custodio made it three 16 minutes from time. Seba scored a consolation goal for the Estoril.
Elsewhere, Nacional lost 1-0 at home to Arouca, with Pintassilgo getting the only goal of the game four minutes from time. Arouca's win makes it two on the bounce after they started the season with back-to-back defeats.
