The rest of the Catfish (29-18) picked up where Royster left off as John Matulia hit a two-run single in the eighth to knot the game,6-6, and Matthew Fields blasted a go-ahead two-run shot, his 15th, in the ninth.
Quinn Stewart also cranked a two-run homer in the third, his 20th, and third in three games. Nevin Ashley doubled in the ninth to extend his hitting streak to 10 games and scored two runs for Columbus.
Catfish reliever Ryan Reid (6-4) yielded one hit over three shutout innings with four strikeouts and one walk. Starter Woods Fines allowed two runs on eight hits over four frames and fanned three.
Chris Hatcher went 3-for-4 with a two-run homer in the fourth and a career-high four RBIs. Scott Cousins chipped in a solo shot, his 13th, for the Grasshoppers (22-27).
Royster's 24th home run of the season puts him in the South Atlantic League lead.
Starter Woods Fines returned from the DL, pitching 4 innings, allowing 2 runs on 8 hits, striking out 3.
The win gives the Catfish a split with with Greensboro and pulls them to within 1/2 game of division-leading Asheville.
Columbus opens a 4-game series at the Northern Division-leading Hickory Crawdads (Pirates) this evening. Hickory has won 6 straight. The Catfish have won 12 of 16.