JUPITER, Fla. -- A day after being hit by, as he described it, a "double-whammy" of discomfort, Cardinals manager Mike Matheny was back in the dugout on Saturday.

Bench coach Mike Aldrete served as manager in Kissimmee, Fla., on Friday while Matheny was dealing with food poisoning and a herniated disc that was radiating pain into his right leg.

Matheny said he had a bulging disc that bothered the left side of his body in 2006, his final year with the Giants. He managed it sufficiently enough at the time, though the recurrence of pain this week will be addressed with an epidural shot on Monday morning. Matheny said that he does not anticipate that affecting his availability to run workouts and manage the team later that day.

"I was wondering how long I'd be able to make it with my back," he said. "I don't know what happened to make it go to the other side. It might just be that it's a weakened area. It's all a part of the joys of catching."

Top prospect Miller shines in debut

JUPITER, Fla. -- Shelby Miller may have the been the Cardinals' last rotation candidate to debut this spring, but his outing against the Nationals on Saturday served as a reminder that he shouldn't be overlooked.

Miller entered in the fourth inning, threw 12 pitches and made the Nationals' hitters look uncomfortable en route to striking out the side. He allowed Ian Desmond's solo homer in the fifth, though he avoided any other trouble on a day when the wind was blowing out of Roger Dean Stadium.

"It drags when you see your teammates out there competing and you're in the dugout waiting to throw," Miller said. "But I feel like I'm where I actually need to be. Last year, I didn't feel like I was up to where the other pitchers were. I was behind and wasn't pitching as good as I should have been. Now I feel like I'm where I need to be and that I'm competing really well."

Miller had been scheduled to make his spring debut last weekend until shoulder soreness stalled his throwing program. The setback was minor, and the right-hander looked anything but rusty during his two-inning appearance.

"He was making good pitches," manager Mike Matheny said of the former first-round Draft pick. "I think it's going to be very helpful as he spends time with [catcher] Yadi [Molina] and watches how Yadi uses his instincts. I think [Shelby] grew up a lot last year in the game and all the way around."

Miller is competing against Joe Kelly and Trevor Rosenthal for the final spot in the Cardinals' rotation. Rosenthal has already logged five Grapefruit League innings. Kelly pitched two scoreless innings in his debut on Friday.

Though Miller may not be starting many Grapefruit League games as the month progresses, he will be building his pitch count up so that he can handle a starting load by the time the season starts. What he does in those appearance will go far in helping to dictate where he'll be making his April starts.

"My ultimate goal is to be a starter in the big leagues for a very long time, and I feel like this is a great opportunity to start that career in St. Louis," Miller said. "I'm just trying to compete and win it and let everybody know that I'm ready for that role. Having a good spring would open some eyes to let people know I'm ready.

"I feel like I'm in a good spot right now. The biggest thing is getting more starts under my belt and letting Mike and the staff know I'm ready to win the spot."

Hobbled Beltran still set to join Puerto Rico

JUPITER, Fla. -- For St. Louis Cardinals outfielder Carlos Beltran, progress was something as simple as being able to put a tennis shoe on his right foot on Saturday morning.

It was a mundane feat, but one that Beltran couldn't accomplish a day earlier due to the swelling of his small right toe. Beltran was hit on the toe by a pitch on Thursday, and he hasn't been available to play since.

"It's a little better, but it's still bruised and still swollen," Beltran said on Saturday, after taking some swings in the batting cage. "It's painful. But I have to do something related to baseball."

For now, the injury will not affect Beltran's status for the World Baseball Classic. He and teammate Yadier Molina are scheduled to join Team Puerto Rico on Sunday in Lee County, Fla, where they will play in exhibition games against the Red Sox and Twins early next week before beginning pool play on Friday.

Beltran said he will make a final determination about his availability for the Classic over the next frew days.

"I'll see how I progress and see what happens," he said. "I don't have to make a decision today."

"He and I talked," added manager Mike Matheny. "If there's one guy who I know is only going to do what he can do, it's him. He's not going to push it. It's still real black and blue. He's going to go and do what he can."

The Cardinals will lose two other players to the Classic after Saturday's game. Mitchell Boggs (USA) and Fernando Salas (Mexico) will both travel to Arizona for their first-round games. Team USA and Mexico face off on Friday.

Motte, Boggs refining craft this spring

JUPITER, Fla. -- Despite the success that Cardinals relievers Jason Motte and Mitchell Boggs had in their late-inning roles last season, both are spending Spring Training with a narrowed focus on getting better.

Boggs is learning to incorporate a slide step into his motion, which the Cardinals hope will help their setup man better control the running game. Last year, Boggs' time to the plate was about 1.5 seconds. The club would like to reduce that to somewhere in the 1.3-1.4 range.

Runners were 6-for-6 in stolen-base attempts against Boggs in 2012.

"Everybody has a list of things to work on, and that's one that Mitchell knows," manager Mike Matheny said. "When he comes on in the eighth inning and a runner gets on base, that's a big deal. He has to be able to slow down the running game. He's working on it."

As for Motte, he's experimenting with his changeup. According to fangraphs.com, only 1.5 percent of the pitches Motte threw in 2012 were changeups. The year before, that percentage was almost negligible (0.1 percent).

But if the Cardinals closer likes how the pitch (which is about 8-10 mph slower than his fastball) works for him this spring, Motte will consider it among his options this season.

"It's something that he's going to try to develop to be a big league pitch," pitching coach Derek Lilliquist said. "If he has his four-seam [fastball], a two-seam [fastball], a cutter and a changeup, that's just going to be another weapon. He's going to continue to throw it. and we'll see what it looks like."

Worth noting

• The Cardinals still have not publicly projected when Allen Craig (right shoulder soreness) will see game action at first base. He did serve as the team's designated hitter again on Saturday and knocked in his fourth run of the spring in the first inning and his fifth in the third inning against the Nationals. Once Craig is cleared to play the field, he'll also do some outfield work in order to prepare himself for fill-in time there this season.

• Even though Rafael Furcal speculated earlier in the week that he'd be ready to play shortstop in Saturday's game, the Cardinals had no intention of sending him out there. The team continues to be cautious with the veteran, who is nursing a bone spur in his right elbow.

• The first of three off-days for the Cardinals is approaching, and Matheny indicated that there will be little to no activity going on at the team's complex on Tuesday. The off-day will allow an extra day of rest for the team's starters.

"I don't mind how long Spring Training is, but what I've always minded in the past is these guys don't get days to shut it down," Matheny said. "It's even unrealistic compared to our season. Some of these guys are in here fighting for jobs, and they show up here every single day thinking they have to do something.