Both of the hopeful starters are scheduled to have a significant workload vs. Atlanta, with Kelly expected to get the start -- though general manager John Mozeliak said on Monday it wasn't important which one got the starting nod.
"It's conceivable that you'd want to see 55 pitches out of both of them, but I'm not going to do that if they throw 40 in the first inning, obviously," pitching coach Derek Lilliquist said. "So it's all based on what it looks like Thursday and, from there, we'll evaluate and move forward."
To this point, Kelly and Miller have each made two spring appearances, and -- statistically -- it's hard to declare a clear front-runner. Kelly sports the better ERA (2.25 to Miller's 5.40 mark) and has limited opponents to a .143 average, but he has issued five free passes while striking out just one batter. Miller, meanwhile, has four strikeouts to just one walk.
Kelly brings more experience to the table, having made 24 appearances (16 starts) last season to Miller's six outings (one start). For now, the focus will be on what each pitcher brings to the table for the remainder of Spring Training -- and it starts Thursday.
"The obvious thing is, moving forward from here, we're running out of starts for guys," Lilliquist said. "They'll both get an opportunity to pitch Thursday, they'll both get an opportunity to get their work in, and we'll just keep evaluating and see what's best for the Cardinals."
Paul Casella is a reporter for MLB.com. Follow him on Twitter @paul_casella. This story was not subject to the approval of Major League Baseball or its clubs.