The next man up mantra is the necessary approach for a team dealing with injuries. A starter goes down, and ideally the next player on the depth chart fills in without the team missing a step.

But avoiding that situation is preferred, and the Chiefs enter Thursday's season opener at New England in better shape on the defensive side than they've been in a while, with stars such as linebackers Justin Houston and Derrick Johnson giving themselves a thumbs-up on health issues.

Houston and Johnson started only three games together last season, with Houston battling a knee injury and Johnson's season ending with a torn Achilles tendon.

For Houston, it's been a frustrating couple of seasons. After his dominant 2014 season, when he piled up 22 sacks, Houston tore his ACL and has appeared in just 16 regular season games since then.

He played in the team's three postseason games over the last two years, but saw only eight snaps in the playoff loss at New England after the 2015 season.

"When I went there a couple of years ago, honestly I wasn't supposed to play," Houston said. "I did it because I didn't want my team to be out there without me. Now, it's night-and-day difference. I'm 100 percent better than where I was."

That's great news for a Chiefs team that handed Houston a six-year, $101 million contract with $52.5 million guaranteed after the 2014 season.

Even with Houston inactive or less than 100 percent, the Chiefs had plenty of positive defensive developments in 2016, finishing third in the AFC in points allowed and tying for the NFL lead in turnover differential.

"He's one of the most dynamic players in the league," Patriots quarterback Tom Brady said of Houston. "He's a factor on every play."

Johnson, who missed the final three games and the playoff loss to the Steelers last season, took 73 defensive snaps in three preseason games.

This marks his second return from an Achilles' tear, although on different legs. The original injury occurred in the 2014 opener. The timetable is accelerated with this comeback, but Johnson believes he's ready.

"We'll see on Thursday night," Johnson said. "I think I am back where I left off. The more games I play, the more reps I get, the better I'll be. ... Hats off to the Chiefs training staff for getting me back and ready to go."

Safety Eric Berry has been fighting a heel injury that he suffered at training camp. He didn't appear in a preseason game, but he didn't hesitate to declare himself fit. When asked about his heel, Berry said, "It's doing great," adding that he could have played if the regular season opened last week.

The Chiefs are not without injury issues on defense. Cornerback Steven Nelson was placed on injured reserve Sunday because of a core muscle injury. Nelson underwent surgery Tuesday and is expected to miss at least half the season.

Otherwise, the Chiefs' defense appears to be in good shape, and it will have to be going against the defending Super Bowl champions in their stadium and facing Brady, whom Johnson, a 13-year veteran, calls the "best I've faced, and still playing at a high level."