"If I miss my next start, I do," Kelly said. "It's early in the year. It's best to be precautionary."
If the Cardinals need to cover a short-term absence, expect them to summon left-hander Tyler Lyons, who pitched for Triple-A Memphis on Wednesday. Lyons is already on the 40-man roster, he is lined up on Kelly's schedule and he has pitched well this month with Memphis. Lyons allowed one run on five hits and a walk in seven innings on Wednesday. He struck out four.
In his three season starts, Lyons is 2-0 with a 3.32 ERA. He made eight starts for St. Louis last season, posting a 5.56 ERA and a 1.305 WHIP.
The Cardinals also have the option to turn to right-hander Carlos Martinez, who was beaten out by Kelly for the final starting job this spring. Already dealing with some bullpen instability, though, the Cardinals are hesitant to pull Martinez out of his setup role unless they needed a long-term replacement for Kelly.
"I think we could [call on Martinez], but I'm not sure that's the way we're going to [go] right now," Cardinals manager Mike Matheny said. "He's been extremely valuable to us and [has] done a nice job down there."
The Cardinals, who are in a stretch of 20 games in 20 days, will next need a fifth starter on Monday. If they want to fortify their bullpen in the meantime, the organization could put Kelly on the disabled list immediately, summon a reliever and then make another roster move when the fill-in starter is needed.
Seth Maness (27 pitches) and Keith Butler (26 pitches) each had strenuous outings on Wednesday.
Kelly's afternoon ended after just 45 pitches when he came up hobbling after trying to beat out a bunt with two out in the fifth. He immediately summoned head trainer Greg Hauck, who, along with Matheny, accompanied Kelly on a slow walk back to the dugout. Maness, who was summoned from the bullpen to take over in a game the Cardinals trailed 1-0, allowed three Milwaukee runs in the fifth.
"I definitely tweaked it, and it's something I felt instantly," Kelly said. "I called the trainer over and let him know and came out of the game. I can walk just with a little limp. We'll see what happens."
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. This story was not subject to the approval of Major League Baseball or its clubs.