HOUSTON — J.J. Watt is out until at least December and could miss the rest of the season with an injured back, leaving the Texans searching for ways to deal with the loss of the NFL’s best defensive player.

Watt was placed on injured reserve on Wednesday, which means he’ll be out for a minimum of eight weeks.

“You can never replace the best player in the NFL,” coach Bill O’Brien said. “When someone like that goes down, it’s a tough thing obviously, but at the same time … this is a team.

“A team made up of some really good veteran leaders, some really good young players. We’re looking forward to the challenges that are ahead.”

O’Brien said Watt had re-injured his back and putting him on IR was the best thing for his long-term health.

“It’s flared up to the point where he can’t continue to play right now,” O’Brien said. “Going on IR will give J.J. all the time he needs to make sure that he’s 100 percent healthy and back to being himself.”

The team was still exploring the injury and it’s unclear if it will require surgery.

Watt, who has won the Defensive Player of the Year for the past two seasons, missed training camp and Houston’s four preseason games after surgery in July to repair a herniated disk in his back. The defensive end started each of the team’s three regular-season games and got hurt again Thursday against the Patriots.

Some have wondered if Watt’s latest setback came because he returned too quickly from surgery in July. O’Brien dismissed that suggestion.

“J.J. did absolutely everything he could do to get back on the field after surgery this summer,” he said. “He followed his doctor’s orders, he played it smart. He passed every test before being cleared to play.”

Watt is the latest star player to suffer a significant injury this season after Dallas quarterback Tony Romo, Minnesota running back Adrian Peterson and Cleveland Browns quarterback Robert Griffin III have all been placed on injured reserve in recent weeks.

Watt tweeted a statement that did not provide details on his injury.

“This won’t be fun, but it is necessary in order for me to return to 100 percent and play at the level that I am capable of playing at,” the post said.

“Everybody deals with adversity in their lives, many much worse than what I’m going through. I have great people around me and I appreciate the thoughts and well wishes from all of you.

“I am looking forward to the fight back to the top and to the next time that I can step back on that field with my brothers to play the game that I love.”

It’s a major setback for Houston, which selected Watt with the 11th overall pick in the 2011 draft. Watt has played 83 consecutive games for the Texans despite various injuries, including torn core muscles and a broken hand last season.

Defensive coordinator Romeo Crennel wouldn’t say who would start in his place on Sunday against the Titans, but acknowledged that everyone on defense will need to pitch in.

“When you have that kind of ability and that kind of playmaking it’s hard to replace with one guy,” Crennel said.

“So we’re going to ask all the guys on defense to pick it up, to put a little extra in it and see if we can gain some of those plays that J.J. used to make.”

Though the coaching staff isn’t pointing at one player to make up for the loss of Watt, the Texans could certainly use a big season from Jadeveon Clowney .

The top overall pick in the 2014 draft has started to show progress this season after failing to make much of an impact in his first two injury-filled seasons.

With Watt relegated to the sideline, he knows that people will be looking to him to show the talent that made him a No. 1 pick.

“Other guys … including myself got to step up and try to replace him,” Clowney said. “So I’m looking forward to big things out of the front and the other guys around to pick it up for him.”

This was a tough offseason for Watt, who had surgery in January to repair five torn core muscles before going under the knife again in July to repair his back.

Watt, who led the NFL with 17½ sacks last season, has 1½ sacks this season to give him 76 for his career .

The 27-year-old is a three-time Defensive Player of the Year winner and a four-time Pro Bowler.

He’s been a force since entering the league not only because of his pass-rushing prowess, but also because of his uncanny ability to swat down passes. He has 45 passes defended in his six-year career. He has forced 15 fumbles and recovered 13.

The Texans signed veteran defensive end Antonio Smith to take his spot on the roster.

The Texans did get a bit of good news on Wednesday amid dealing with Watt’s injury with linebacker Brian Cushing returning to practice for the first time since spraining the medial collateral ligament in his right knee in the season opener. His status for Sunday’s game is uncertain.

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