A goal from Maranhao after 71 minutes was enough to sink Uniao, who had Marcos Paulo dismissed in the last minute.

Porto will have the chance to stretch their lead once more when they face Nacional on Monday.

In today's other game, Rui Sampaio's 50th-minute equaliser earned Beira Mar a point against 10-man Maritimo.

Baba Diawara had given the visitors a 36th-minute lead, but life became difficult once Kleber was dismissed four minutes later.