Dallas Cowboys quarterback Tony Romo is out with another back injury.

During a conference call with reporters Saturday, coach Jason Garrett said an MRI on Friday revealed that Romo, 36, has a broken bone in his back. According to a Dallas Morning News source, Romo is expected to miss six to 10 weeks.

Garrett declined to put a timetable on Romo's return.

“We don't feel like this fracture in his back has anything to do with the other back issues he's had in the past,” Garrett said. “It's a separate incident. We're confident that he's going to come back and play football for us this year.”

On the third play of Thursday night's preseason game at Seattle, Romo took off and went into a slide as Seahawks defensive end Cliff Avril came over the top. Romo landed awkwardly with the full weight of Avril pressing down on him. While on the ground, Romo immediately grabbed his back.

The Cowboys drafted Dak Prescott late in the fourth round this year. The former Mississippi State standout has had an impressive preseason, completing 39 of 50 passes for 454 yards, five touchdowns and no interceptions. He has also run for two touchdowns.

Prescott is expected to be Dallas' starter in Romo's absence.

Extension for Tavon Austin: Wide receiver Tavon Austin (Dunbar) has signed a four-year contract extension with the Los Angeles Rams.

NFL.com reported that the deal was worth $42 million with $30 million guaranteed.

“Tavon has been an integral part of our offense and special teams since we drafted him in 2013,” coach Jeff Fisher said in a statement. “It is important to our organization to retain players we've drafted and invested in, and Tavon is an example of that. We're excited for him to continue his career with the Rams.”

In three seasons, Austin has 19 touchdowns: nine receiving, seven rushing and three on punt returns. He scored 10 touchdowns last season, tied with running back Todd Gurley for most on the team.

Austin caught 52 passes for 473 yards last season and rushed for 434 yards and four touchdowns.

Kaepernick's anthem protest: San Francisco 49ers quarterback Colin Kaepernick is refusing to stand for the national anthem before games because he believes the United States oppresses African-Americans and other minorities.

Kaepernick sat on the team's bench Friday night during the anthem before the 49ers lost to the Green Bay Packers, 21-10, in a preseason game. He later explained his reasoning in an interview with NFL Media.

“I am not going to stand up to show pride in a flag for a country that oppresses black people and people of color,” Kaepernick said. “To me, this is bigger than football and it would be selfish on my part to look the other way. There are bodies in the street and people getting paid leave and getting away with murder.”

NFL spokesman Brian McCarthy said Saturday that “players are encouraged but not required to stand during the playing of the national anthem.”

Kaepernick, who is biracial, was adopted and raised by white parents. He has been outspoken on his Twitter account on civil rights issues and in support of the Black Lives Matter movement.

Preseason games:Sam Bradford continues to make his pitch to be the Philadelphia Eagles' starting quarterback.

On Saturday night, he threw mostly strikes.

With Carson Wentz, the No. 2 overall pick in the draft, missing a second straight game because of fractured ribs, Bradford led the Eagles on three touchdown drives and to a third straight preseason victory, 33-23, over the host Indianapolis Colts.

Bradford has been virtually flawless in each of his three starts. This time, he was 17-for-20 for 167 yards with two touchdown passes and one interception. He played into the third quarter and led the Eagles to scores on four of their first six possessions.

Eli Manning was 10-for-15 for 65 yards and an interception while playing one series into the third quarter as the New York Giants defeated the New York Jets, 21-20.

Jets quarterback Ryan Fitzpatrick was 9-for-16 for 76 yards with the score and lost a fumble before being replaced by Geno Smith just before halftime.

Marcus Mariota led Tennessee to scores on all four drives he played and Derek Carr threw two touchdown passes for Oakland and the Titans beat the host Raiders, 27-14.

Trevor Siemian threw his first touchdown pass of the preseason and tightened his grip on the Denver Broncos' starting quarterback job in a 17-9 win over the visiting Los Angeles Rams.

Siemian completed 10 of 17 passes for 122 yards.

Alex Smith completed 20 of 30 passes for 181?yards and led three scoring drives in helping the Kansas City Chiefs beat the host Chicago Bears, 23-7.