Grandal, a switch-hitting catcher just called up from Class AAA Tucson Friday, socked a solo shot in the fourth inning while batting right-handed to break a scoreless tie with his first major league hit
His second career hit was also a homer. The rookie's two-run shot while batting left-handed against Jeremy Guthrie (3-7) in the sixth erased a 2-1 Padres deficit and provided the difference as San Diego evened its three-game set at Coors Field.
Grandal became the first player in MLB history whose first two career hits were homers from different sides of plate in same game.
Alexi Amarista also socked a pair of homers, driving in four runs for San Diego.
Edinson Volquez (5-7) collected the victory, yielding two runs (one earned) on three hits over six innings despite allowing six walks. He struck out eight.
Wilin Rosario homered for the Rockies.