Sampson struck out two in one scoreless inning on Thursday against the Pirates, and Price considered the short outing similar to a bullpen session. However, Price added that it wasn't necessarily planned out that way when Sampson was put into the ballgame on Thursday.
"We didn't know when he pitched that day that he'd be the Sunday starter, so it wasn't a prelim to the Sunday start," Price said. "We made that decision -- it gelled, probably last night to sometime this morning. We'd spoken about it, spoke about it with [Reds president of baseball operations and general manager] Walt [Jocketty] as opposed to going out there and trying to bring up a guy from Triple-A. It made sense to give Keyvius an opportunity to start.
"It's a spot start," Price said. "There's no guarantees beyond tomorrow, but it does give us a better chance to look at him and give him a chance to use his full mix."
Sampson will be the 12th Reds pitcher to make a start this season, with six of those being rookies. If he remains in the rotation, the Reds will have a five-rookie rotation now that Johnny Cueto and Leake have been traded.
Despite being used out of the bullpen on Thursday, Sampson has served as a starter this season in the Minor Leagues. Between Triple-A Louisville and Double-A Pensacola, Sampson is 3-6 with a 3.38 ERA in 16 appearances, including 15 starts, this season.
Price said he is hoping Sampson can build off an impressive eight-scoreless-innings performance in his last start with Louisville on July 24.
"First of all, we targeted him as a guy that we felt would give us depth in our starting pitching for the 2015 season, and that we felt he had some untapped potential when we got him from San Diego," Price said. "He scuffled a little bit in Triple-A. However, he seemed to turn the corner. He had a real nice eight-inning outing in his last start there, eight scoreless innings. He threw the ball beautifully. He did some good work with [pitching coach] Ted Power there in Louisville. We kind of felt like this is an opportunity for him to feed off that."
Robert Bondy is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.