* Crucial errors in seventh gives Cards win
* Ortiz belts fifth homer of postseason (Adds quotes, details)
By Larry Fine
BOSTON, Oct 24 (Reuters) - The St Louis Cardinals turned the tables on Boston by taking full advantage of some sloppy Red Sox fielding to level the World Series at 1-1 on the back of a 4-2 victory at Fenway Park on Thursday.
The Cardinals, who committed three errors in losing Game One of the best-of-seven series 8-1 a day earlier, latched on to a pair of miscues in the seventh inning to score three runs and overhaul the hosts.
"We kind of contributed to the three runs allowed," said Boston manager John Farrell, echoing the post-mortem delivered on Wednesday by his St Louis counterpart, Mike Matheny.
"Uncharacteristic of the way I think we've taken care of the baseball this year."
St Louis rallied after David 'Big Papi' Ortiz erased a 1-0 Cardinals lead with a two-run homer over the 'Green Monster' in the sixth inning off rookie pitching sensation Michael Wacha.
Wacha gave up three hits in six innings to register the win and improve to 4-0 in the postseason after two great innings of relief from Carlos Martinez set up Trevor Rosenthal for the save, which he posted by striking out the side in the ninth.
"I felt the bullpen did a great job," Matheny said.
The 22-year-old Wacha, who entered the game having allowed just one run in playoff 21 innings, prevailed again despite not being at his sharpest.
He walked four batters and threw only 65 strikes of his 114 pitches but wriggled out of jams and combined with the two relievers on a four-hitter.
Matheny, however, said he continued to be impressed by Wacha.
"I don't know what else you could ask," he said. "Put him on any stage and he does a real nice job of limiting distractions."
John Lackey was an unlucky loser for Boston, charged with three runs on just five hits in 6-1/3 innings.
Wacha and Lackey had been locked in a taut pitchers' duel through five innings with the Cardinals leading 1-0 thanks to a lead-off triple in the fourth by Matt Holliday, who scored on a soft grounder by Yadier Molina.
Clutch-hitting Ortiz hammered his fifth home run of the postseason with Dustin Pedroia aboard to put Boston 2-1 ahead in the sixth and send the sold-out Fenway crowd into raptures.
However, the joy was short-lived as the Cards dealt the Red Sox a killer blow in the seventh.
After allowing a walk and a single, Lackey gave way to lefty reliever Craig Breslow.
A double steal by St Louis put runners on second and third with one out and a walk to Daniel Descalso loaded the bases.
Matt Carpenter then flied out to left and outfielder Jonny Gomes unleashed a throw to the plate, hoping to nail pinch-runner Pete Kozma at home.
The bullet throw arrived just as Kozma slid in but was slightly wide of the mark.
Catcher Jarrod Saltalamacchia stretched to make the catch and try a sweep tag, but did not control the ball as Kozma scored.
Breslow, backing up the play, tried to throw out John Jay as he raced toward third but his attempt sailed over the head of third baseman Xander Bogaerts and allowed Jay to score.
A single by Carlos Beltran, who returned to the lineup after suffering a rib injury in Game One, brought Descalso home to cap the three-run salvo in which Saltalamacchia and Breslow were charged with errors.
The series now shifts to St Louis for the next three games with Game Three scheduled on Saturday.
"Excited to get home. I know everybody is," Matheny added. "Being able to take the World Series back to St Louis and have our home fan base supporting us.
"These last couple of days... it meant a lot to be able to play here in Fenway. It's a pretty unique experience for a lot of guys that have never played here before to be able to do it on this stage. But there's no place like home." (Editing by John O'Brien and Greg Stutchbury)