Smoltz joined the NL Central leaders shortly after he cleared waivers, following his release by Boston. He was 2-5 with an 8.33 ERA in eight starts for the Red Sox.
General manager John Mozeliak said Smoltz will start Sunday at San Diego, and probably would get at least a few turns in the rotation. Mozeliak said Smoltz didn't ask to start as a "negotiating ploy."
"He had very little demands," Mozeliak said on a conference call. "He had no demands. From everything he had heard about this club, he was excited to take this opportunity. The reason for the start was just to get him work and know what we have."
The Cardinals hope Smoltz either can fill a void as the fifth starter or provide right-handed relief in the bullpen. Detroit, the Los Angeles Dodgers, Texas and Florida also were said to be interested in signing the longtime Atlanta star, but Smoltz preferred pitching in the National League.
"We feel that this is an opportunity to strengthen our pitching staff," Mozeliak said in an earlier statement. "When you have an opportunity to bring the expertise and experience of a future Hall of Famer to your club, it's easy to see why we are excited about the prospects of what John Smoltz can do to improve our team's chances as we approach the stretch drive."
One of the best big-game pitchers of his era, Smoltz is expected to be with his new team Thursday when St. Louis plays at San Diego. The former Cy Young Award winner is the latest high-profile acquisition -- with Matt Holliday -- in a makeover that helped the Cardinals stretch their division lead to six games over Chicago.
The risk for the Cardinals is small -- Boston is responsible for the bulk of the contract. St. Louis is on the hook only for a prorated share of the major league minimum, about $100,000 through the rest of the season.
The Cardinals lobbied Smoltz with telephone calls from manager Tony La Russa, pitching coach Dave Duncan and infielder Mark DeRosa, a former teammate in Atlanta.
"These situations are unique because the players out there, you're not really negotiating a salary," Mozeliak said. "What you're trying to do is figure out how a player is going to fit in."
Smoltz is 212-152 with a 3.32 ERA and 154 saves in 21 seasons. An eight-time All-Star, he's the only pitcher in major league history with 200 wins and 150 saves.
Smoltz debuted with the Braves in 1988 and spent his entire career in Atlanta before signing a one-year, $5.5 million contract with the Red Sox in January. Still recovering from shoulder surgery that forced him to miss most of the 2008 season, he didn't pitch until June, and never got on track in Boston.
The Red Sox cut Smoltz on Aug. 7, a day after he lost at Yankee Stadium in one of the worst starts of his career. Left-handed hitters were especially rough on him this year, batting .444 overall.
Smoltz, however, did show flashes of his former sharpness, even in that final start. In that first inning against New York, retired Derek Jeter on a grounder and struck out Johnny Damon and Alex Rodriguez.
The Cardinals' most pressing need is for a fifth starter behind Chris Carpenter (13-3, 2.27 ERA), Adam Wainwright (14-7, 2.62 ERA), Joel Pineiro (11-9, 3.25) and Kyle Lohse (5-7, 4.58), who has shown signs of coming around from a forearm injury.
Todd Wellemeyer, the fifth starter most of the season until being sent to the bullpen last month, is 7-9 with a 5.67 ERA. Mitchell Boggs, who has filled the role in recent weeks, is 1-2 with a 4.58 ERA. Overall, the team's fifth starters are 10-16, and there is no immediate help available from the minor leagues.
Smoltz had said he preferred to go to a team where he could start.
Since June, the Cardinals have acquired DeRosa, infielder Julio Lugo and, most prominently, a new cleanup hitter in Holliday. All three have contributed mightily as St. Louis has turned what was a tight race in the NL Central at the All-Star break into a big lead over the second-place Cubs.
Smoltz also brings intangibles as the Cardinals seek to return to the postseason for the first time since winning the 2006 World Series.
"He's the most competitive guy I've ever been around and one of the best teammates I've ever had," DeRosa said after Tuesday night's 7-3 loss at Dodger Stadium.
Smoltz holds the record for postseason wins. He is 15-4 with four saves and a 2.65 ERA in the playoffs and World Series.
As a starter, Smoltz has won 14 or more games 10 times, including 1996, when he won the NL Cy Young Award after going 24-8 with a 2.94 ERA for the Braves.
Installed as the closer after missing 2000 and most of 2001 following elbow surgery, he had 10 saves down the stretch in 2001 then 144 saves over the next three seasons -- 55 in 2002, 45 in 2003 and 44 in 2004.