Clippers rookie Sindarius Thornwell is making the most of new opportunity

His playing time had diminished with the Clippers while other guards around him played more, leaving Sindarius Thornwell out of a rotation he once was a part of after his early-season success.

His confidence began to fade along the way, leaving Thornwell questioning his abilities during his rookie season.

But the 6-foot-5 guard never stopped working, always preparing himself for the next opportunity that Thornwell hoped would come again.

And when he got that chance to start again Friday night against the Cleveland Cavaliers, Thornwell was ready because he had never stopped toiling.

“Everybody did a good job of staying in my ear, just telling me to be ready, keep working,” Thornwell said. “They told me to treat the practices like games.”

Thornwell, a second-round draft pick, had been a pleasant surprise earlier this season.

His defense kept him on the court. His offense was slow to develop, but he never stopped working.

But his last start was Dec. 15 at the Washington Wizards and his playing time began to dwindle after that.

“I think it’s been a roller coaster for him,” Clippers coach Doc Rivers said. “I thought he started out great. I don’t know what wall he hit — rookie wall. Some wall.

“But he kind of lost his focus and got comfortable a little bit. Give him credit. We sat him for a long time and he worked every single day. He’s worked on his game with our staff and now he’s ready again and we need him.”

There was a point in which Thornwell was playing behind guards C.J. Williams and Tyrone Wallace, two players the Clippers had signed to two-way contracts to play for their NBA development league team, the Agua Caliente Clippers of Ontario.

Thornwell just had to wait for his opportunity.

“It was hard because you still want to play,” Thornwell said. “So I just came in and treated my workouts, my practices, everything like it was a game so that when it was time to play, it was kind of easy to step in and be ready for it.”

Injuries kept hampering the Clippers, finally leading to Thornwell playing some more.

Starting guard Avery Bradley remains out with a sports hernia. Starting forward Danilo Gallinari remains out with a nondisplaced fracture of his right hand. Starting guard Patrick Beverley is out for the season after having right knee surgery.

“We were down on guards,” Rivers said. “We needed another player and he stepped up at the right time.”

When Thornwell went back into the starting lineup against the Cavaliers, he was tasked with having to defend LeBron James.

Thornwell accepted the challenge and scored a career-high 14 points.

Thornwell just smiled as he talked about his last start being against James and his very first start Nov. 10 against Oklahoma City and being assigned to defend Thunder All-Star Paul George.

“I don’t know, man. I guess it’s just Doc’s way of seeing if I’m ready to play,” Thornwell said. “He just wants to see if I’m focused and locked in. But my starts are always on somebody tough.”

broderick.turner@latimes.com