Elaine Thompson/Associated Press

Tony Romo's optimism after injuring his back during Thursday's preseason game against the Seattle Seahawks gave way to some disappointment, as the Dallas Cowboys quarterback received the news he suffered a fractured bone due to Seahawks defensive end Cliff Avril's hit.

Cowboys head coach Jason Garrett confirmed Romo's diagnosis on Saturday, per Clarence Hill of the Fort Worth Star-Telegram.

According to Hill, Garrett initially said he wasn't ruling out Romo for Week 1 against the New York Giants on Sept. 11 because the quarterback has played through back fractures in the past. However David Moore of the Dallas Morning News reported rookie Dak Prescott will be the team's starter in their opener.

David Helman of the Cowboys' official website added that Garrett is considering the situation a day-by-day thing and has no set timetable for Romo's return.

However, Pro Football Talk is reporting that Romo will miss six to 10 weeks as a result of the injury. Hill reported Romo may return against the Philadelphia Eagles in Week 7.

Romo told reporters after the game that he felt fine when he initially took the hit from Avril.

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"Whenever you take a hit, that was a perfect-timed situation," Romo said, per ESPN.com's Todd Archer. "I was going into a slide. But in a weird way, I feel good about the fact that was probably as tough of a hit I've taken on the back as I've had in the last five years. From that regard, I feel very lucky that it can hold up and I can keep going."

Hill reported the Cowboys sent Romo for an MRI on Friday morning after he woke up in pain and his back began to stiffen up.

Prescott has been the talk of this preseason. The fourth-round pick is 39-of-50 with seven total touchdowns (two rushing) and no interceptions through three exhibition games.

While the Cowboys planned to start the season with Romo under center, they will need to throw Prescott into the fire quicker than anyone expected.

The Cowboys do have reasons to be hopeful Romo can play quicker than many anticipate. He played through a broken rib and back problems during the team's 2014 season, when the Cowboys won the NFC East.

But at 36 years old and after missing 12 games last season thanks to two separate injuries to his left collarbone, Romo is rapidly wearing down his body. There won't be a perfect solution in Dallas with two weeks before the regular season begins.