Guillermo Moscoso (5-6) took advantage of the run support, all of which came in two innings, in taking the win.
He gave up three hits and two runs -- one earned -- in six innings. Three relievers allowed a total of two hits, including a J.P. Arencibia home run in the seventh.
By then the A's had posted a six-run rally in the third inning and a four-run rally in the sixth and led 10-2.
Matsui had an RBI single in the third and scored on Conor Jackson's two-run triple. Jackson capped the rally by scoring on a wild pitch. All those runs were charged to Toronto starter Brad Mills (1-2).
The sixth-inning outburst was fueled by and error and three walks along with a run-scoring single by Matsui, a Jackson sacrifice fly and a two-run single by Ryan Sweeney.
Moscoso walked two but both came around to score in the Toronto fourth, one on an error and the other on a hit by Edwin Encarnacion.
Arencibia's home run was his 19th of the year.