A's call up former 1st-rounder Green
Green was the No. 13 overall pick of the 2009 draft out of USC and was rated as the A's top prospect by Baseball America as recently as 2011.
He had yet to appear in a major-league game prior to Monday but was called up after batting .318 with 11 home runs and 49 RBIs in 81 games with Triple-A Sacramento.
Infielder Adam Rosales was designated for assignment after hitting .200 with four home runs and eight RBIs in 48 games with Oakland.
Manager Bob Melvin said the A's were hopeful to keep Rosales within the organization if he is not claimed on waivers.
Melvin said the intention is for Green to play every day. The 25-year-old was tied for second in the Pacific Coast League in runs (61) and hits (112). He batted .372 in June.