ST. LOUIS -- Pleased with the progress Jaime Garcia made during four Minor League rehab starts, the Cardinals will insert the left-hander back into the rotation on Sunday. The start will come against Pittsburgh, and the timing of it allows Garcia to get his normal four days of rest after pitching on Tuesday.

In his last Minor League appearance, Garcia tossed 93 pitches in Tuesday's five-inning start for Triple-A Memphis. He returned to St. Louis on Wednesday and declared himself fully healthy and ready to contribute.

"I have some confidence back and I feel like my timing is where it needs to be with my pitches," Garcia said. "Most importantly, my shoulder is feeling good. When you rehab from a shoulder, it's tough to get the feeling back, the feeling of making pitches and trusting your stuff. It's a little more complicated than the elbow. But like I said, this start was definitely big for me to get some of that confidence back."

Garcia's return gives the Cardinals a left-handed starter for the first time since Garcia's last start, which came on June 5. He lasted only two innings and gave up six runs in that outing. The next day, Garcia was placed on the disabled list and diagnosed with a left shoulder impingement.

He shut down from throwing for about a month before restarting the process of strengthening his shoulder. And by eclipsing the 90-pitch mark on Tuesday, Garcia should be ready to throw at least 100 pitches in his first start back.

In the 11 starts Garcia made before landing on the DL, he went 3-4 with a 4.48 ERA. Ten of the 33 earned runs he allowed came in the two starts that immediately preceded Garcia's shutdown.

"It's tough to say that the team needs me because the starting pitchers have been doing an unbelievable job," Garcia said. "But I'm definitely really excited. I've been working hard these two months to get back out there and try and help my teammates."

In order to make room for Garcia to rejoin the rotation, the Cardinals have announced plans to move Joe Kelly to the bullpen. Kelly made 12 starts for St. Louis while Garcia was sidelined.

Molina day-to-day with back tightness

ST. LOUIS -- Yadier Molina was out of the Cardinals' lineup on Wednesday night against Arizona while dealing with middle-back tightness. The discomfort in Molina's back began prior to Tuesday's game against the D-backs in St. Louis, and the Cardinals catcher expects to miss at least a day or two.

"Hopefully today with treatment it can better," Molina said on Wednesday afternoon. "Tomorrow, we'll see where we are."

Molina said he felt the tightness in his back during pregame work in the bullpen on Tuesday, but chose to play regardless. Molina was 0-for-3 with a walk and was not running well, prompting manager Mike Matheny to sub in backup Tony Cruz to catch the ninth inning of an 8-2 win.

Molina said he'd been dealing with soreness in his left side for nearly two weeks after he'd aggravated the area stealing third in a game against Milwaukee on Aug. 3. That injury was not serious, but Molina believes his back may have tightened because he was attempting to not put as much pressure on his side.

"He's pushing right now because he knows everybody needs to push," Matheny said. "But he's going to have to sit for at least today, and we'll have to see how he feels tomorrow."

Cruz got the start on Wednesday, hitting seventh in the Cardinals lineup. He is batting .226 with eight RBIs in 32 games (19 starts) this season.

Matheny said Molina could be available to pinch-hit or catch a few innings on Wednesday if needed. While Molina admitted his tight back limits him in his movement, swinging and running, he said he'd gladly step up if called upon.

"I put some heat on it, and let's go," Molina said.

Matheny thinks Kelly will adjust well to bullpen

ST. LOUIS -- A night after pitching a career-best 6 1/3 innings in the Cardinals' win over Arizona, Joe Kelly learned that he will be moving into the bullpen to make rotation space for Jaime Garcia.

The relief role, while foreign to Kelly at this level, is actually something he knows quite well. Before making 23 relief appearances as a Cardinals farmhand, Kelly served as a closer on his UC Riverside team. At the time he was drafted in 2009, Kelly held the UC Riverside career record with 24 saves.

"He understands the mindset. He understands what it's like coming out of the bullpen," manager Mike Matheny said. "I think he'll adjust quickly to it. I think he's going to come back throwing a little harder."

Because he threw 97 pitches on Tuesday, Kelly won't be available out of the bullpen until Saturday, at the earliest. If the Cardinals can avoid using him until at least Sunday, that would give Kelly his normal four days of rest.

With Kelly unable to contribute immediately, the Cardinals will wait until after Saturday's game to activate Garcia and make a corresponding move that would send a reliever back to Triple-A.

Adding Kelly to the bullpen seemingly strengthens a unit that has, at times this season, been quite inconsistent. Kelly can fill a variety of roles, too. Though the Cardinals don't intend to designate Kelly as a long reliever, he certainly has the arm strength to be able to offer multiple innings of relief. Matheny said that he also won't hesitate to use Kelly in late-inning situations.

"We're excited about Joe Kelly and his future in this organization," Matheny said. "I know he's not going to be flustered by the situation. As time goes, we'll figure out exactly how that plays out. It'll work itself out."

It was Garcia's injury that initially opened a rotation spot for Kelly in early June. Since then, Kelly has made 12 starts. He's finished at least six innings in eight of them and allowed more than three earned runs in an outing only once.

Sending Kelly to the bullpen is also an indication that the Cardinals are not overly concerned by Lance Lynn's workload. Lynn, in his first full season as a big league starter, has logged 138 innings. That puts him only 26 innings away from his career-high total, set in 2010.

But instead of slowing down Lynn's inning accumulation, the Cardinals have opted to have him continue to start.

"More than anything, you have to look at the body of work of what Lance has been able to do this season. It's been special," Matheny said of Lynn, who leads the staff with 13 wins. "Lance has really done a nice job with the opportunities that have come. And the amount of work that he has taken on physically hasn't been an issue."

Worth noting

• If Yadier Molina (middle back tightness) is unavailable and the Cardinals are in a situation where catcher Tony Cruz also has to exit the game, Daniel Descalso lines up as the team's third catcher. Matt Carpenter and Ryan Jackson would also be candidates to catch in an emergency situation.

• Rafael Furcal has made six straight starts at shortstop since receiving a cortisone injection to help with his ailing lower back. Furcal is 2-for-16 since that injection, though he has not looked as uncomfortable in the field as he did before the shot.

"I think by the way he's moving ... and there seems to be a little more finish on his swings, I think those are all good signs that the shot has helped him," manager Mike Matheny said. "But right now we just want him to get healthy and hopefully the swing comes along with the health."

• With his scoreless appearance on Tuesday, reliever Edward Mujica has still not allowed a run since being acquired by the Cardinals at the non-waiver Trade Deadline. Mujica has limited opponents to four hits in those 5 2/3 innings, and he has picked up five holds.

• Since moving to Class A Advanced Palm Beach, 2012 first-rounder Michael Wacha has tossed eight scoreless innings. He's allowed just one run and one walk, while striking out 16.