BUENOS AIRES, Feb. 20 (Xinhua) -- Alexis Castro scored in the second half as Group A leader Estudiantes continued its impressive start to Argentina's Apertura season with a 1-0 home win over Sarmiento on Friday.

Castro put his side ahead just after halftime with an acrobatic first-time shot.

The visitors could only manage two shots on target despite controlling almost 60% of possession.

The result leaves Estudiantes with 12 points from six games, a point clear of second-placed Velez Sarsfield.

In other Argentine top flight fixtures on Friday, Instituto Cordoba won 2-1 at home to Atletico Tucuman, Boca Juniors was held to a goalless home draw by Racing Club, and Belgrano drew 1-1 at Defensa y Justicia. ■