Boca Juniors capped its Argentine Apertura championship by defeating Olimpo Bahia Blanca 2-0 in the last round on Sunday at Bombonera stadium.Matias Silvestre scored off a header in the 14th minute and Rodrigo Palacio made it 2-0 in the 59th for a seventh straight win for Boca, which won the tournament last week.It was Boca's fourth cup in less than a year, after the South American Recopa and Copa Sudamericana, and the Clausura championship.Boca ended with 43 points, followed by Lanus with 35, River Plate with 34, Gimnasia Jujuy on 33, and Gimnasia La Plata at 32.River Plate defeated host Quilmes 3-1 in a match which was suspended in the 67th minute because of fan violence.Boca, Gimnasia La Plata, River, Banfield and Velez will play in the 2007 Copa Libertadores. The same teams plus Lanus and San Lorenzo will strive to wrest the Sudamericana from defending champion Boca.Instituto and Tiro Federal were relegated to second division.Argentinos Juniors and Olimpo will play with two teams from second division, and the two winners of the home-and-away series will play in the first division next season.