One of three hits by Duomit was a two-run homer.
Jones also had three hits, including a two-run double and Steve Pearce hit a two-run single. Lastings Milledge, Andy LaRoche and Andrew McCutchen each had one RBI for the Pirates, who can sweep the three-game series with a victory Sunday.
Winner Zach Duke (10-11) yielded two runs and eight hits in seven innings.
Jonny Gomes led Cincinnati with three hits and one RBI. Wladimir Balentien drove in a run for the Reds, who sank to 11-31 since the All-Star break.
Losing pitcher Justin Lehr (2-1) surrendered six runs and eight hits in five innings.