Arias, who entered the game batting .138 with two RBIs, went 3-for-4 with three RBIs. His first-inning single, which drove in two runs, was his first hit since May 9 and ended an 0-for-14 skid.
Morse, who leads the Giants with 11 home runs, 38 RBIs and a .574 slugging percentage, fouled a pitch off his foot during Saturday's 2-0 loss to St. Louis. He had started all but four of San Francisco's games.
Manager Bruce Bochy said that Morse's injury wasn't serious and expected the slugger to start Tuesday night's series opener at Cincinnati in left field, which requires less footwork than first base. Bochy added that Buster Posey likely will play first base, with Hector Sanchez catching.