St. Louis had a two-run lead when Matt Holliday popped to short center field. Boston's Jacoby Ellsbury rushed toward the infield, but the ball bounced off his glove for an error.
Thinking he could gain another base, Holliday -- who had driven in a run on a single in the first -- made the wide turn around first, but Red Sox starter Jake Peavy quickly dashed to cover second, and Holliday was caught too far from both bases.
Red Sox second baseman Dustin Pedroia grabbed the ball and threw to first, where David Ortiz made the easy tag.
The play killed any chance to score more runs, with Matt Adams striking out to end the inning.
Thomas Harding is a reporter for MLB.com. Read his blog, Hardball in the Rockies, and follow him on Twitter @harding_at_mlb. This story was not subject to the approval of Major League Baseball or its clubs.