Maybin was injured while stepping on third base as he was trying to score from first on Donnie Murphy's double. He hobbled home before being escorted to the clubhouse by a trainer. He is not expected to play for at least several days.
Maybin says he is sore and he hopes it is "just a day-to-day thing."
McClellan set the pace with a sharp three innings before Hill allowed a run in his two innings.
McClellan, a right-hander, allowed a hit and struck out four while throwing just 39 pitches. The left-handed Hill gave up two hits, including a solo home run by Brett Carroll, and struck out two.
"They both know that there is a spot open," Cardinals manager Tony La Russa said. "They're not pitching for show. They're trying to be the guy."
Marlins starter Sean West walked three and gave up a hit in two innings.
McClellan, Hill and prospect Jaime Garcia are the candidates for the final spot in the rotation behind Chris Carpenter, Adam Wainwright, Brad Penny and Kyle Lohse. McClellan has been a staple of the Cardinals bullpen the last two years with a 3.73 ERA in 134 appearances.
"I feel like I've been preparing for this game for six months," McClellan said. "Now I've got four days to get ready for the next one. I know I'm going to be prepared physically and mentally."
McClellan has started 12 games, all in the minors, since 2005.
"What I'm going to try to focus on is making them hit the ball, making them put it in play and be aggressive," McClellan said.
"I worked hard this offseason to get here and I felt like it showed a little bit today. There's still a lot more pitches to throw and innings to throw," he continued. "I just need to stay right where I'm at and keep building on each one."
Hill signed in January after having surgery in August to repair a tear in his shoulder cartilage. He was 3-3 with a 7.80 ERA in 14 appearances last season with the Orioles.
"The velocity is there," Hill said. "I think that's not going to be a problem."
Hill said he is putting the injury out of his mind.
"If you're going out there and think like that, you're probably going to be tentative," he said. "You're not going to be aggressive. I've been out there and been tentative when my shoulder wasn't feeling that great, it's like a shark tank out there. They'll eat you alive."