Boston had grown accustomed to bullying opponents into submission in the World Series but the Red Sox realize they have a fight on their hands after the St Louis Cardinals rallied to win at Fenway Park on Thursday.

"We fully expected this to be a hard-fought series," Red Sox manager John Farrell said after the visiting Cards dealt Boston a 4-2 defeat at a chilly Fenway Park to tie up the best-of-seven series at 1-1.

"Not surprising that we're in this position we are."

The Cardinals committed three errors in their opening 8-1 loss to the Red Sox on Wednesday to extend Boston's World Series winning streak to nine following four-game sweeps of the same opponents in 2004 and the Colorado Rockies three years later.

This season's Cards are made of tougher stuff, however, and the visitors took advantage of a pair of Red Sox miscues in a three-run seventh to overturn a 2-1 deficit and seize a winning lead.

"In the seventh inning, we kind of contributed to the three runs allowed," Farrell said about an inning that undid the good work of starting pitcher John Lackey.

"I thought John Lackey threw the ball very well," the manager said. "The lead-off walk starts to get things going for them. After the base hit to (Jon) Jay, felt like we were in a pretty good situation for a match-up."

DOUBLE STEAL

With the left-handed Daniel Descalso due up, Farrell replaced Lackey with southpaw Craig Breslow. Pinch-runner Pete Kozma and Jay then executed a double steal and Breslow walked Descalso to load the bases.

A fly ball to left by Matt Carpenter triggered a sloppy sequence that paved the way for St Louis to take control. The throw home by leftfielder Jonny Gomes pulled catcher Jarrod Saltalamacchia toward first and the ball got by him.

Breslow, backing up the play, tried to nab Jay heading for third base but his throw sailed over the third baseman's head, allowing the runner to score and Descalso to sprint to third. Carlos Beltran delivered the third run with a single.

"Looking back, I'm sure Craig would like to have that ball back and hold it with a chance to shut down the inning right there," Farrell lamented.

"Uncharacteristic of the way I think we've taken care of the baseball this year. And it contributed to the three runs."

Farrell was disappointed but by no means downcast ahead of the next three games of the series in St Louis, staring with Game Three on Saturday..

"This team has responded well to challenges on the road or at home," he said. "I know that we'll be ready to go on Saturday over there."