Andrew Luck watched one last game from the sideline Saturday.

Then he said goodbye to the NFL.

The Indianapolis Colts quarterback heard boos as he walked away from the field, then walked to a podium and made his surprise decision official. The oft-injured star is retiring at age 29.

"I'm in pain, I'm still in pain. It's been four years of this pain, rehab cycle," Luck said. "It's a myriad of issues — calf strain, posterior ankle impingement, high ankle sprain. Part of my journey going forward will be figuring out how to feel better."

Luck wasn't planning to make the announcement following Saturday's 27-17 loss to the Chicago Bears. But when ESPN first reported the news during the fourth quarter, Luck moved up his plan for a Sunday afternoon announcement and held a 25-minute impromptu news conference.

At times his voice cracked with emotion.

One thing was clear: The endless barrage of injuries stripped away his joy for the game.

The Colts starter now is Jacoby Brissett, a fourth-year player whom the Colts acquired in a cutdown weekend trade two years ago. He went 4-11 in the 2017 season.

Indianapolis had already been preparing for the possibility Luck might not be ready for the Sept. 8 season opener against the Los Angeles Chargers. Luck was diagnosed with a strained left calf in March and he missed all of the team's offseason workouts.

He returned to limited action when training camp opened in late July. After three practices, though, the lingering pain near his ankle forced him back into rehab.

It wasn't just the leg. He played with shoulder pain for most of 2015 and 2016, and his 2015 season ended when he suffered a lacerated kidney. He missed all of 2017 following shoulder surgery.

"I am going to retire," Luck said. "This is not an easy decision. It's the hardest decision of my life. But it is the right decision for me."

Etc.

• Panthers coach Ron Rivera said he expects quarterback Cam Newton (left midfoot sprain) to return to practice "pretty soon."

• Lions coach Matt Patricia said injuries to linebacker Jarrad Davis and center Frank Ragnow are not season-ending. Davis went down with an injured right leg, and Ragnow had to be helped off the field during the Lions' loss to Buffalo on Friday night.

• Patriots tight end Lance Kendricks was suspended without pay for the first game of the season for violating the NFL's policy on substance abuse.

Saturday's preseason games

Dallas 34, Houston 0: Texans quarterback Deshaun Watson didn't get the longer preseason look he wanted, especially after running back Lamar Miller was injured on the second play. Watson got dropped twice in three plays on the first series and didn't return. Dak Prescott of the host Cowboys threw a 12-yard TD pass to Michael Gallup.

Chicago 27, Indianapolis 17: Tyler Bray completed 11 of 16 passes for 136 yards and one touchdown while Ryan Nall had two carries for 76 yards as the Bears beat the host Colts. Chad Kelly of Indianapolis was 16-for-21 for 209 yards and one touchdown.

San Francisco 27, Kansas City 17: Quarterback Jimmy Garoppolo of the visiting 49ers was 14-for-20 for 188 yards. He threw a touchdown pass to running back Matt Breida and set up Robbie Gould for two field goals. The Chiefs' Patrick Mahomes finished 8-for-10 for 126 yards.

New Orleans 28, New York Jets 13: Drew Brees threw a 19-yard touchdown pass to Michael Thomas to cap his only drive in his preseason debut in the Saints' road win. Sam Darnold of the Jets was 8-for-13 for 97 yards and one touchdown, too.

L.A. Rams 10, Denver 6: John Wolford's 4-yard scoring pass to Jalen Greene with 12:38 left in the fourth quarter gave the host Rams the win.

Seattle 23, L.A. Chargers 15: The balanced Seahawks rushed for 185 yards and three touchdowns on 42 carries — six players all had between 20 and 32 yards — to beat the host Chargers.