DETROIT -- Albert Pujols' triumphant return was spoiled by a rookie.
St. Louis reliever Mike Parisi (0-4) gave up a leadoff single to Curtis Granderson and intentionally walked Carlos Guillen and Miguel Cabrera before Thomas drew his second run-scoring walk of the day.
"You want to be the guy and get the big hit and win the game, but a walk is just as good," Thomas said. "It was a great feeling."
Detroit manager Jim Leyland praised the 24-year-old's concentration.
"He showed a lot of composure," he said. "That's pretty impressive for a young hitter."
Pujols, in his first game back from the disabled list, hit an RBI single in the ninth to give the Cardinals the lead. Gary Sheffield, who returned Tuesday from the disabled list, answered with a solo homer for Detroit in the bottom of the inning.
Pujols, who missed 13 games with a calf injury, was 4-for-4 with an intentional walk.
"I just kept loose, kept (the injury) off my mind and looked for good pitches," the six-time All-Star said. "I wasn't surprised about my day. I work hard for everything that I do."
Manager Tony La Russa said before the game that Pujols, who was the designated hitter Thursday, could return to first base if he showed no ill effects. The slugger didn't seem to create any doubt.
"Today he showed you how truly great a player he really is," La Russa said.
Sheffield passed Andre Dawson for 32nd place on the career list with his 1,592nd RBI.
Reliever Bobby Seay (1-1) worked the 10th for the win.
Detroit scored the game's first run when Cardinals reliever Ron Villone surrendered a bases-loaded walk to Thomas in the bottom of the sixth, but St. Louis answered in the seventh when Brendan Ryan came home on a fielding error.
Detroit starter Nate Robertson, seeking his fourth victory in as many starts, surrendered 11 hits but stranded eight St. Louis runners in 6 1/3 innings. His counterpart, Cardinals right-hander Todd Wellemeyer, pitched the first four innings before giving way to Villone.
Tigers second baseman Placido Polanco was ejected by umpire Paul Schrieber in the sixth for arguing a called third strike.
"That's all part of the game," said Leyland, who had to restrain the normally mild-mannered Polanco. "I don't have any problem with that."
The Tigers are 14-5 and have won their last five series since Oakland completed a three-game sweep on June 4.
"We're trying to creep back into this thing," added Leyland, whose team trails idle Chicago by five games in the AL Central. "We've made some headway."
Both teams were late to the ballpark after Wednesday's rain-delayed game didn't end until almost 1 a.m. Even La Russa was a tardy arrival.
"It was a tough game," he said after the Cardinals dropped their second straight. "There isn't a lot to say. We just came out on the wrong end."
- The Cardinals placed LHP Randy Flores on the 15-day disabled list with left ankle tendinitis. His departure leaves the club with just one left-hander -- Villone.
- Granderson extended his hitting streak to a career-best 14 games.
- Detroit C Dane Sardinha, called up from Triple-A Toledo on Wednesday, made his Tigers debut behind the plate.
- St. Louis is 1-5 against the Tigers since defeating them in the 2006 World Series. The teams will meet again next season in interleague play.
- Detroit rookie Mike Hollimon had his first two major league hits.