ST. LOUIS -- Insisting that his lower back is "fine," Matt Holliday nonetheless remained out of the Cardinals' lineup for Wednesday's series finale against the Mets.

Manager Mike Matheny intended to give Holliday the day off well before Holliday exited Tuesday's 5-1 victory over New York with back tightness. Holliday has played more games than anyone else on the club this year and had started 44 straight games through Tuesday.

Holliday, who said that he felt healthy enough to play on Wednesday, left Tuesday's game after drawing a walk in the seventh inning. It was on his way toward first base that Holliday said he felt discomfort in his lower back.

Starting in left field in place of Holliday against R.A. Dickey on Wednesday was Shane Robinson, who collected two of the Cardinals' seven hits against the knuckleballer in the team's 5-0 defeat on June 2.

Holliday, who ranks ninth in the National League with a .305 batting average, is expected to return to the lineup on Friday. His 92 RBIs are third best in the league.

Miller's debut for Cardinals a complete success

ST. LOUIS -- For all the attention Shelby Miller's arrival had garnered on Tuesday, it was Wednesday's events that everyone had been waiting to see.

Touted as one of the most talented pitchers to rise through the Cardinals' farm system in years, Miller made his much-anticipated debut in Wednesday's 6-2 loss to the Mets. It went as well as Miller could have scripted it. In two scoreless innings, Miller allowed one single and struck out four.

"This is obviously a moment to remember," Miller said. "It was really nerve-wracking. Once I settled in, it went a lot smoother."

Miller's first out was a bit controversial, as it took all four umpires huddling before the crew ruled that catcher Tony Cruz made the catch on a foul pop near the screen behind home plate. Miller then closed out the sixth with a groundout and a strikeout, getting Mike Baxter to swing through a 94-mph fastball.

Miller struck out the side in the seventh, with the string interrupted only by Daniel Murphy's one-out single.

"I'm happy for Shelby," manager Mike Matheny said. "It was a nice way to break into the league. It was a good test for him. Any test your first day in the big leagues is tough. He did a nice job, did everything we asked."

Facing Major League hitters wasn't the only first for Miller on Wednesday. He also made his first appearance out of the bullpen -- aside from Spring Training and the Futures Game -- since being taken as the 19th overall pick in the 2009 First-Year Player Draft.

Miller said the most challenging aspect of the change in roles came in the timing of his warmup. He estimated that he threw about 20-25 warmup pitches -- the same number he would throw before a start -- and also had the benefit of coming in at the start of an inning.

"Having a little more time [to warm up] probably made me more comfortable out there," Miller said. "You can't really always expect to have that much time going in. That's one thing that I'll have to get used to. At the same time, I think things went really smoothly, and I think I'm going to have a better feel in the future."

Berkman and Beltran in; four regulars out

ST. LOUIS -- On a day when manager Mike Matheny sat four of his regular starting position players, he also infused some experience back into the lineup with the returns of Lance Berkman and Carlos Beltran.

Beltran's absence from the starting lineup was brief, as he missed just two games due to a bone bruise on his left knee. For Berkman, however, the start was his first since Aug. 2. It also came as a surprise given how much Berkman had been hobbling even since coming off the disabled list over the weekend. Berkman has been bothered by soreness in both of his knees.

"It feels like I'm being held together with super glue and with tape," Berkman said. "But the reality is it's probably not that bad. Really, what it is now is more of a confidence issue and just having confidence in the joint. That's a real thing. It's not a pain thing. It's more that I'm a little tentative to push it because of what's happened in the past.

"Getting these looks and getting some reps in there is kind of what you have to do to get the feel back."

Matheny did not anticipate having the option to start Berkman this soon. Rather, the expectation was that Berkman would be limited to contributing off the bench. Berkman's availability, though, changed after a conversation he had with Matheny during Tuesday's game.

"He told me he's feeling pretty good," Matheny said of Berkman. "I talked to him about the opportunity today with some of these guys being out, and he said, 'Absolutely.' I really wasn't thinking that much about a start. I really just wanted to get him some at-bats pinch-hit-wise. He told me he's ready to do whatever."

Berkman is still not expected to get many starts down the stretch.

The presence of Berkman and Beltran in the lineup somewhat mitigated the absence of several other mainstays. Yadier Molina, Matt Holliday, David Freese and Allen Craig each received the day off, and Matheny's decision on that regard was two-fold.

For various reasons, all four appeared in need of a day off. Holliday and Molina are both dealing with minor injury issues, while Freese and Craig have already played more this season than either has before in the Majors.

And then there was the knuckleball factor.

"There's been thought in the game that a guy like that can really foul up something that you have going really good," Matheny said, hours before his club faced 17-win knuckleballer R.A. Dickey. "Sometimes it just messes with their approach because you have to have a completely different approach. We can get some of these young players who are just champing at the bit in there swinging off anybody."

All four of the regulars Matheny rested on Wednesday were available, if needed, off the bench.

Cardinals offer postseason ticket opportunity

ST. LOUIS -- Fans wanting to purchase tickets to potential 2012 playoff games at Busch Stadium can now begin registering for that chance through an online-only lottery on cardinals.com.

By registering once, fans will be eligible to purchase tickets for all three postseason rounds, as well as a potential home Wild Card game. How many seats will be made available to the general public through this lottery system will be determined at a later date.

To be eligible for the chance to buy tickets to the National League Wild Card game and Division Series, fans must be registered by Sept. 13. There is a Sept. 27 deadline to sign up in order to be eligible for NL Championship Series tickets, and an Oct. 11 deadline for World Series ones.

Winners of the lottery system will be notified via e-mail for each round.

For more details on the lottery process and/or to register, go to cardinals.com/postseason.

Worth noting

• Michael Wacha, the Cardinals' top pick in the 2012 First-Year Player Draft, will not participate in the organization's upcoming instructional league. The Cardinals do not want to add any additional workload to the right-hander's season.

After pitching 113 1/3 innings for Texas A&M University this spring, Wacha has thrown another 21 on three Minor League levels. Wacha is also a part of the Double-A Springfield club that begins a playoff series on Wednesday.

• MLB.com will launch updated prospect rankings on Thursday. New Top 20 lists for each club will be unveiled, and MLB.com will also announce its picks for the Top 100 prospects in baseball. Shelby Miller entered 2012 ranked by MLB.com as the Cardinals' top prospect.

• The Cardinals will open a three-game series against the Brewers on Friday. Lining up as Milwaukee's probable pitchers for the series are Yovani Gallardo (14-8, 3.79 ERA), Mike Fiers (8-7, 3.11 ERA) and Shaun Marcum (5.4, 3.53 ERA). The Cardinals are 5-1 against the Brewers at Busch Stadium this year.