Terry Francona, who managed the Boston Red Sox to two World Series championships after 86 years of futility and then was unable to stop the biggest September collapse in the history of Major League Baseball, is out.

The Red Sox said today they won’t exercise their option to extend Francona’s contract for the 2012 and 2013 seasons, ending an eight-season term for Francona that began with the team’s first championship since 1918 and ended with them blowing a nine-game lead for a playoff spot in September.

“We met this morning to look back on the 2011 season and to consider the future of the Boston Red Sox, including my involvement with the club,” Francona said in a statement released by the club. “I passed along my frustrations at my inability to effectively reach the players. After many conversations and much consideration, I ultimately felt that, out of respect to this team, it was time for me to move on.”

New York Yankees manager Joe Girardi, speaking minutes before the Red Sox released the statement about Francona’s departure, said his Boston counterpart was in a tough position.

“There’s expectations. A lot of times they’re extremely high expectations when you’re in certain towns,” Girardi said as the Yankees prepared to open their American League Division Series tonight against Detroit. “We understand that when we take the job. High expectations are better than no expectations.”

Francona, 52, was 744-552 in eight seasons with the team. He won World Series titles in 2004 and 2007, and made the playoffs five times.

The Red Sox led the Tampa Bay Rays by nine games for the AL wild-card playoff spot on Sept. 4 and went 7-20 in September, missing the playoffs on the season’s final day. The collapse was the biggest in the final month of a season, according to the Elias Sports Bureau.

Boston was eliminated on Sept. 28, the final game of the regular season, when the team surrendered two runs in the bottom of the ninth against the Baltimore Orioles and the Rays rallied from seven runs down to beat the New York Yankees in extra innings.

“We’ll go down in history as one of the worst collapses,” Red Sox left fielder Carl Crawford told reporters after the season. “It definitely doesn’t feel good to be part of that.”

The Red Sox acquired Crawford and first baseman Adrian Gonzalez, both four-time All-Stars, in the offseason last year and lost the first six games of the 2011 season, their worst start since 1945. They recovered to claim a share of the AL East division lead with the Yankees on May 26, and competed for the top spot with New York before the late-season collapse.

Boston’s seven wins in 27 games this month was its worst performance since it finished 1952 with the same record in September.

Francona spent 10 years as a first baseman and outfielder with five teams prior to coaching. He managed the Philadelphia Phillies from 1997-2000 before being hired by the Red Sox before the start of the 2004 season.

“He proved to be an unflappable leader for our major league club, displaying consistency, calmness, hard work, thoughtfulness, a sense of humor, and faith in the players even at the most difficult of times,” Red Sox General Manager Theo Epstein said in the team’s release. “Without Tito’s commitment over eight years, we would not be the organization we are today. Nobody at the Red Sox blames Tito for what happened at the end of this season; we own that as an organization.”