CLEVELAND — The Browns passed their first prime-time test. The second one won’t be nearly as easy. Here come Aaron Donald and those big, bad Los Angeles Rams.

The defending NFC champions, with an offense teeming with talent and defense led by incomparable star tackle Donald, will visit Cleveland in the Browns’ first nationally televised Sunday night game in 11 years.

To make matters worse for Cleveland, the Browns have been beset by injuries, including to linebacker Christian Kirksey.

The Browns placed their linebacker and defensive captain on injured reserve Saturday, a move that will sideline him for at least eight games. Kirksey missed the final seven games last season after he was put on IR with a hamstring injury.

Kirksey’s loss is another shot to the Browns (1-1), who placed starting tight end David Njoku on IR with a broken right wrist on Friday. Cleveland could also be down several more starters — and maybe its entire secondary — for tonight’s game against the Rams.

Kirksey is believed to have suffered a torn pectoral muscle during the second half of Monday night’s 23-3 win over the New York Jets. It’s still possible he’ll have season-ending surgery.

A leader and well-respected player in Cleveland’s locker room, Kirksey will be replaced in the starting lineup by rookie linebacker Mack Wilson. The Browns’ fifth-round pick from Alabama got some playing time against the Jets after Kirksey got hurt.

“Mack did well,” coach Freddie Kitchens said. “I do not know what he recorded stat wise, but I think he had 11 or 12 plays and four tackles or something like that.”

With Kirksey out and linebacker Adarius Taylor questionable with an ankle injury, the Browns promoted undrafted rookie linebacker Willie Harvey from the practice squad to the active roster.

Safety Damarious Randall (concussion) was formally declared out by coach Freddie Kitchens following practice Friday. Safety Morgan Burnett (quadriceps), linebacker Adarius Taylor (ankle) and cornerbacks Denzel Ward (hamstring) and Greedy Williams (hamstring) are listed as questionable.

“Kind of a bummer, isn’t it?” Kitchens said. “It does make things more difficult, but we preach preparation. That goes for backup guys, just as it does for the starters, because once you’re in the game, you could become a starter in one play. Nothing has really changed from that aspect.”

Cornerbacks T.J. Carrie and Terrance Mitchell and safeties Eric Murray and Jermaine Whitehead are set to move into the starting lineup, along with Wilson. Cleveland has a 1-1 record and its defense is ranked seventh in the NFL.

The secondary shuffling isn’t as problematic as it appears as Carrie and Mitchell are sixth-year pros who played significant roles for the Browns in 2018. Whitehead started the first two games as a fifth defensive back and Murray logged 42 defensive plays against the Jets.

Quarterback Jared Goff and the Los Angeles offense have had some issues, but Donald and the rest of the defense are playing at a high level already. They shut down New Orleans last week, helped by Donald inadvertently sidelining Saints quarterback Drew Brees with a thumb injury.

Browns star Odell Beckham Jr. said Donald will have everyone’s attention.

“There’s no way to even go around him,” said Beckham. “He’s probably the best player in the league. If not the best player in the league, one of the most disruptive players I’ve ever seen. So, yeah, No. 99 has to be accounted for. The game plan starts right there. They have a lot of other stars, a lot of very, very talented, great players, but it starts with 99.

“So we have to get that handled, and we’re going to be tested in every position.”

DONALD, DUCK

The two-time AP Defensive Player of the Year, Donald has no sacks and just two tackles through two games. The numbers are deceiving as teams are scheming to stay clear of Donald. The Browns will probably do the same.

“Everybody is sliding to him,” defensive end Michael Brockers said. “He’s going to get a lot of attention, and that’s what’s happening now. It’s leaving a lot of opportunities for other guys to make plays. As the season goes on, they’re going to have to pick their poison on which guys to block, and that’s when it’s going to get really fun.”

It didn’t get fun for Donald until Week 4 last year. He have record a sack in his first three games and still finished with 20 ¢.

THROW IT

Mayfield has been guilty of holding onto the ball too long, and not taking advantage of receivers being open while trying to complete long passes.

He’s still getting into a rhythm with Beckham, who sat out the preseason but showed why he’s elite on Monday by scoring on an 89-yard play.

“It’s a learning curve,” said Mayfield, who while not as accurate as usual has still completed 60 percent of his throws. “Needing to know when I can take my shots and check the ball down to get completions. It’s a little difficult at times but, like I keep harping on, I just need to get completions.”

LINE WORRIES

The Browns could exploit inexperience up front for the Rams, who are likely to have three untested starters on their offensive line.

Right guard Austin Blythe is unlikely to play due to a left ankle sprain. If he becomes the first starting offensive lineman to miss a game due to injury in McVay’s tenure, sixth-round pick Jamil Demby is expected to make his first start alongside fellow 2018 draft choices Brian Allen at center and Joe Noteboom at left guard.

Allen and Noteboom will be making their third career starts. Left tackle Andrew Whitworth and right tackle Rob Havenstein haven’t been spectacular so far this season, either.

GURLEY GOES

Rams running back Todd Gurley has fond memories of the team’s last meeting with the Browns: Gurley scored his first two NFL touchdowns against Cleveland during a 128-yard performance as a rookie in St. Louis in 2015.

Gurley is a quiet ninth in the league this season with 160 yards rushing on 30 attempts. Backup Malcolm Brown has 17 carries as the Rams attempt to lessen the load on Gurley, who leads the NFL in yards rushing since the start of the 2017 season. Gurley has insisted his knee is fine and he’s ready for any workload.

BEREA, Ohio (AP) — The Cleveland Browns could be without six defensive starters, including their entire secondary, when they host the defending NFC champion Los Angeles Rams.

Randall, Burnett and Taylor sat out all three practices this week, while defensive captain Kirksey is out indefinitely and may require surgery for his unspecified injury that occurred Monday during the Browns’ 23-3 win at the New York Jets.

Ward and Williams did not participate in team drills Thursday and Friday. There is a strong possibility the Rams’ explosive offense — led by quarterback Jared Goff, running back Todd Gurley and wide receiver Robert Woods — could face four fill-in defensive backs.

“We’re going to have to pick up the rush to help the guys in the back end,” defensive tackle Larry Ogunjobi acknowledged. “But I feel like it all works together, so we’ll be all right.

“To be honest, you look forward to situations like this because a lot of these guys come in and play really well. I have confidence because I watch them prepare every day.”

“It don’t matter who is in, you’ve got to have the right mentality and we vets have to rally the young guys,” tight end Demetrius Harris said. “You don’t want to see anybody go down, but football is a business and it’s the next man up.

“We prepare every week — everyone in this room does — that we’re going to win, so I can’t wait until Sunday night.”

Kitchens echoed Harris’ optimism, though he joked that he wouldn’t tell reporters if he felt differently. Los Angeles is 2-0 and has scored the seventh-most points in the league, averaging 28.5 per game.

The first-year coach noted that the 8:20 p.m. kickoff could benefit his questionable players, giving them a little more time to recover, and expects the sellout crowd at FirstEnergy Stadium to be electric.

“I want our fans to come with passion because I promise you the guys that dress are going to play to the best of their ability,” Kitchens said. “I want to play smart, I want to play fast and I want to play physical, whoever is on the team.

“I just need 11 on each side of the ball to show up and play. I will roll with whoever is there.”

NOTES: DE Chris Smith has been excused from all team activities to grieve the death of girlfriend Petara Cordero in an auto accident on Sept. 11. Smith played against the Jets to honor Cordero, who gave birth to their daughter, Haven Harris Smith, last month. “I am hesitant to say whether he is going to suit up or not because I would like to talk with Chris and see, but yes, Chris is doing well,” Kitchens said. “It is still a tough time period for the family.” … TE David Njoku (right wrist fracture) was placed on injured reserve. He can’t be activated until Week 11. Kitchens remained unsure if Njoku will undergo surgery after being hurt against the Jets. …S Juston Burris was claimed off waivers from Oakland, and CB Robert Jackson was promoted from the practice squad. … Fifth-round pick Wilson spent the day away from the team for personal reasons, but was expected back Saturday. … Starting T Chris Hubbard (foot) sat out the week and is questionable. T Justin McCray would replace him.