Carlos Beltran's RBI single capped a three-run seventh and Michael Wacha pitched six solid innings as St. Louis rallied to beat Boston 4-2 and level the World Series.
Carlos Beltran of the St. Louis Cardinals hits an RBI single in the seventh inning against the Boston Red Sox during Game Two of the 2013 World Series at Fenway Park on October 24, 2013 in Boston, Massachusetts
Beltran, who was playing through the pain of a sore right rib cage on Thursday, smacked a two-out single to right field that scored Daniel Descalso for the Cardinals, who knotted the best-of-seven series at one game apiece.
"When I left the ballpark yesterday I had very little hope that I was going to be in the lineup," said Beltran, an All-Star slugger who had to leave game one with a right rib contusion suffered in the second inning when the right fielder dived over a wall to rob Boston's David Ortiz of a grand slam.
X-rays came back negative and Beltran was given the green light to play after taking batting practice with his teammates.
"I was able to get some treatment and find a way to try anything so that I could try to go out there and feel no pain," he said.
Major League Baseball's championship series now shifts to St. Louis for game three on Saturday.
The seventh inning proved the turning point in the roller-coaster contest in front of a crowd of 38,436 at Fenway Park.
The Cardinals engineered a double steal to advance their baserunners, then took advantage of a pair of throwing blunders by the Red Sox to erase a 2-1 deficit.
Descalso walked to load the bases. Matt Carpenter hit a sacrifice fly and Boston's Jonny Gomes' throw to home plate got past Jarrod Saltalamacchia.
Red Sox pitcher Craig Breslow was backing up the play, but his throw to third base was high, allowing John Jay to score.
Beltran, a 17-year veteran who is making his World Series debut, then plated a run with his single to round out the scoring.
Beltran said doctors gave him a pain killer shot of Toradol to allow him to move on the field.
"They gave me an injection to block the pain for five or six hours. I am going to be sore tomorrow," he said.
Rookie flamethrower Wacha, who was making his World Series debut, improved to 4-0 in the post-season.
"It is the World Series, big-time game," Wacha said. "I just tried to use it to my advantage, go out and pitch with some adrenaline and block out the crowd.
"I didn't have my best stuff. I tried to let my defence be behind me and pitch to contact and they made some great plays."
Wacha also got plenty of support from his bullpen as Carlos Martinez was terrific through two innings and hard-throwing closer Trevor Rosenthal struck out the side in the bottom of the ninth to get the save.
The 22-year-old Wacha allowed two runs on three hits and struck out six as he took the win. Martinez fanned three batters in two shutout innings and Rosenthal overpowered Boston pinch hitter Daniel Nava for the final out of the contest. All three pitchers are under the age of 24.
Because of their youth, the St. Louis' bullpen situation seemed a bit shaky heading into the post-season but the young guns are making believers of their critics.
The two clubs are meeting for the fourth time in the World Series, and the first since 2004, when the Red Sox ended their 86-year drought with a four-game sweep.
History could still be on the side of the Red Sox, who routed the Cardinals 8-1 in game one on Wednesday. Nine of the last 10 game-one winners have gone on to win MLB's Fall Classic.
Boston starter John Lackey struck out six in just over six innings of work. Lackey surrendered three runs on five hits and took the loss.
Ortiz clubbed a two-run homer in the bottom of the sixth for the Red Sox, who had their nine game World Series winning streak snapped.
"We fully expected this to be a hard-fought series," said Boston manager John Farrell. "Not surprisingly we are in this position we are. In the seventh inning we contributed to the three runs.
"Uncharacteristic of the way we've taken care of the baseball this year."
The Red Sox will hand the ball to righthander Jake Peavy for game three while the Cardinals are expected to start Joe Kelly.
St. Louis has won 11 World Series with its last coming in 2011 against Texas. Boston, meanwhile, has won seven titles, the most recent a sweep of the Colorado Rockies in 2007.