Ten-man Benfica edged Sporting Lisbon 1-0 thanks to Javi Garcia's first-half goal on Saturday, taking the overnight lead of the Portuguese league.
The Spanish midfielder headed in Pablo Aimar's pass three minutes before halftime for what proved the winner in the Portuguese capital derby.
Oscar Cardozo was sent off with his second booking in the 63rd, but Benfica held on for the win.
The win capped a good week for Benfica, following a draw at Manchester United that booked a place in the knockout rounds of the Champions League.
Sporting fell four points back in third place.
Defending champion FC Porto can draw level on points with Benfica with a win against Braga on Sunday.