Amarista was part of two-run rallies in the second, fourth and seventh innings, when he hit a two-run home run. San Diego's Everth Cabrera collected four hits, scored a run and drove in another while Jedd Gyorko had three hits and two runs scored.
All together the Padres had 17 hits, the first seven of which came against Baltimore starter Freddy Garcia (0-2), who gave up four runs in 3 2/3 innings.
San Diego starter Jason Marquis (5-2) allowed seven of the Orioles' 11 hits and left the game after five innings with a 4-2 lead.
Amarista had a double ahead of John Baker's two-run single in the second, doubled and scored in the fourth after Kyle Banks hit a home run and drove in Banks with a home run of his own in the seventh.
Manny Machado had four hits -- three doubles -- for the Orioles. J.J. Hardy and Matt Wieters hit solo home runs for Baltimore.