HOUSTON (AP) — For a moment, Houston Texans linebacker Zac Diles feared his career might be over after breaking his left leg simply running down the field during a special-teams drill in November 2008.

X-rays showed a clean break, and doctors told Diles that his tibia would heal, allowing him to play again. He dutifully did the rehab and started 14 of 16 games last season — often thinking how lucky he was.

“You have to grow up really fast when something like that happens,” Diles said after Wednesday’s practice. “You learn that you just can’t take stuff for granted. You start thinking, ‘Man, this could’ve all been taken from me.’ You learn to enjoy every moment you’re out here playing, because any moment could be your last.”

He’ll enter his fourth season as one of the top playmakers on Houston’s defense. Coach Gary Kubiak thinks Diles is on a fast track to a memorable career.

“I think he’s on the verge of becoming a Pro Bowl linebacker,” Kubiak said.

The Texans selected Diles in the seventh round in 2007 out of Kansas State. He played in 11 games as a rookie and was playing linebacker by the end of the season.

He earned a starting role at outside linebacker before the next season, then started eight games before the injury. His 66 tackles still ranked second on the team, even though he spent the second half of the year on injured reserve.

Houston drafted linebacker Brian Cushing in the first round in 2009, and Diles started worrying about his future.

“They drafted him and I was like, ‘Wow, I broke my leg and now I’m not going to have a job,’” Diles said. “But things have a way of working themselves out. I’m still in the building.”

Cushing took Diles’ strong-side linebacking spot and Diles moved to the weak side, where he would drop back into coverage and face smaller blockers. Diles accepted the switch and set out to win back his coaches’ confidence.

“I think my performance from before I broke my leg, that reassured them that they could put me out there and trust me to do a good job,” Diles said. “But I had to come into training camp (in 2009) and show them I was ready. I was able to go out there and earn my spot. Like I said, things just have a way of working themselves out.”

Diles made 62 tackles, recovered a fumble and forced a fumble last season for the league’s 13th-ranked defense (325 yards per game). He feels like a seasoned veteran now, with a firm grasp of the position and the Texans’ defensive schemes.

“It just makes the game slower out there when you know what you’re doing,” Diles said. “You can move a lot faster and do more things. I’ve played all three positions since I’ve been here, and that helps a lot, too.”

While Diles feels some job security, he resists the urge to feel too relaxed. He wants competition from younger players, because that will keep him motivated to improve.

“You never want to get too comfortable, because there is always somebody coming up who would love to take your job,” Diles said. “I know all the reads, I know the defense. But this is how we put our food on the table, so there’s always that one guy who would love to come and take it all from you.”