LISBON, Dec. 21 (Xinhua) -- Sporting was held to a goalless draw by Nacional on Saturday, failing to increase its provisional lead of the portuguese league.
Sporting, which was hoping to clinch a sixth consecutive victory in Alvalade Stadium in Lisbon, was under considerable pressure after Porto and Benfica's victories Friday and created poor scoring chances.
Algerian forward Islam Slimani did score in the 64th minute but fans were left bemused when his goal was disallowed by referee Manuel Mota for an alleged foul on Venezuelan striker Mario Rondon.
Nacional showed good defensive work and created a real threat through Brazilian striker Diego Barcellos, whose effort in the 57th minute went wide.
Nacional won the last round against Pacos de Ferreira after four consecutive draws, and is now sixth place in the Portuguese league with 21 points, while Sporting is provisionally at the top and on even points with its rivals Porto and Benfica.
Sporting was without Cisse due to injury and Nacional without Edgar Abreu and Skolnik.