SEATTLE — Old habits die hard. That was the case for the Broncos defense on Sunday.

Denver played a great defense in the first half, recording an interception and two safeties, but that effort fell short on the Seahawks’ first drive of the third quarter.

In six plays, Seattle managed to gain 66 yards, highlighted by running back Kenneth Walker cutting to the right, holding off tackles from inside linebacker Alex Singleton and cornerback Riley Moss and leaping into the end zone for a 23-yard touchdown.

The Broncos vowed to improve their run defense this offseason after ranking among the league’s worst last season. But once again, Denver’s inability to stop the run was their undoing in a 26-20 loss at Lumen Field, with 90 of the Seahawks’ 202 total yards coming on the ground in the second half.

“We can’t give up as many (rushing yards) as we did,” said outside linebacker Jonathon Cooper, who finished with two sacks. “That should be a big emphasis for us next week.”

The defense started the game excellently.

On Seattle’s first play of the quarter, Cooper came home to tackle veteran quarterback Geno Smith for a loss of 7 yards. On the next play, defensive tackle DJ Jones pressured Smith, forcing him to throw an interception to Singleton.

In the second quarter, with Denver’s offense struggling to put points on the board, the defense produced two safeties. It was only the third time in NFL history that a team recorded multiple safeties in a season-opening game. The first came on a holding penalty in the end zone, and the second saw Cooper and defensive end Zach Allen tackle running back Zach Charbonnet behind the goal line on first-and-10.

Denver’s defense also found a way to contain Walker. With eight minutes left in the second quarter, outside linebacker Baron Browning wrapped around Walker before doing a backflip while taking him to the ground for a loss of 4 yards. Walker went into halftime with 17 of Seattle’s 56 rushing yards.

“I thought it was great how we came out of it,” Broncos safety P.J. Locke said. “Our goal was to stop the run game and the defensive line attacked.”

The second half, however, was a different story. The Seahawks scored on three consecutive drives as Seattle pushed the pace.

Denver’s struggles against Seattle’s ground game opened the door for Smith to make plays with his arm. After a 12-yard run from Walker, Smith completed three straight passes, including two to wide receiver Tyler Lockett that set up a 30-yard touchdown reception from Charbonnet early in the fourth quarter.