The Argentine collected the ball near the touchline around 10 metres inside his own half and accelerated away from three opponents. He then burst between two defenders to give himself a clear run on goal and chipped the ball over goalkeeper Matt Jones from around 25 metres.
The eighth-minute goal was the high point of an otherwise scrappy game which ended with Belenenses fuming over a disallowed goal when Tiago Caeiro's second-half effort was ruled out after the referee consulted with the linesman.
Benfica, who have 52 points from 21 games, stayed five clear of Sporting who beat Braga 2-1 on Saturday.
Third-placed Porto (43 points), champions for the past three seasons, dropped further behind when they were held 2-2 at Vitoria Guimaraes after leading 2-0.
Ricardo Quaresma, with a penalty, and Luis Carlos Lica put Porto in control but Moussa Maazou pulled one back before the break and Marco Matias levelled seven minutes after the restart.
Bottom club Pacos de Ferreira gave new coach Jorge Costa a winning start with a 3-1 victory over Maritimo, only their fourth of the season.)
- Sports & Recreation