ARLINGTON, TX - NOVEMBER 26: Tony Romo #9 of the Dallas Cowboys is lead to the sidelines by team officials after being sacked by the Carolina Panthers in the third quarter at AT&T Stadium on November 26, 2015 in Arlington, Texas. Romo left the field following the play. (Photo by Tom Pennington/Getty Images)

Tony Romo has just stunned the NFL and the football world

This happened on the day Dallas was going to release him.

Tony Romo, the long-time Dallas Cowboys quarterback who lost his starting job last year to rookie Dak Prescott last season, has made a shocking decision:

Dallas, according to  ESPN, was set to release Romo today, but he decided to retire out of concerns for his health.

The move comes one day after Dallas owner Jerry Jones notified all 32 NFL teams they could negotiate with Romo and his agents, so long as they talked trade for the 37-year-old quarterback.

With the emergence of Prescott, Romo was the odd-man out in Dallas. He was scheduled to pull down $14 million in base pay this season, a sum that's far too expensive for a backup quarterback. So the retirement helps the Cowboys because, instead of a nearly $25 million cap hit this year (base plus bonus and salary restructure money), the dead cap hit will be spread out to about $11 million this year and $9 next.

Romo had been linked, all off season, to the Denver Broncos and Houston Texans. Neither team was interested in trading for him, though. Denver seemed to grow tired of waiting for Dallas to decide whether they would release Romo, and announced they're comfortable with what they have in Trevor Siemian and Paxton Lynch.

Romo was drafted out of Eastern Illinois in 2004, and has his breakout season in 2006, when he started 10 games and was named to the Pro Bowl.

Romo finishes his career with a record of 78-49. He threw for 34,183 passing yards and 248 touchdowns, and both are the most in franchise history. He also owns the NFL record for throwing touchdown passes in 41-straight road games.

ESPN also listed his other accomplishments:

Team records for most 300-yard passing games (46), multiple touchdown pass games (79) and consecutive games with a touchdown pass (38). In 2012, he threw for a club-record 4,903 yards and on Oct. 6, 2013, against the Broncos, he threw for a franchise record 506 yards.

But it was the injuries that got him. He's suffered two serious back injuries, including fractures in 2014, He's also broken his collarbone twice, and suffered complications from those injuries.