There was nothing easy about the final stretch of C.J. Anderson‘s journey toward 1,000 rushing yards.

But on his 18th carry Sunday, as night fell on a frozen Sports Authority Field, the Broncos’ running back darted up the left side for 10 yards, officially putting him over the 1,000-yard mark for the first time in his five-year career. Anderson also became the first Denver running back since Knowshon Moreno (1,038) in 2013 to reach that plateau.

“It means a lot,” Anderson said as he sat in his locker after the game. “I was an undrafted guy. I’ve put a lot of work in, a lot of hard work. A lot of rehab coming off surgery. It’s a special place.”

The 10-yard run by Anderson, which came early in the fourth quarter, put him at 61 yards for the game and 1,007 for the season.

“I said, ‘Look, man, I need one 10-yard run,'” Anderson said. “I think I’m highly capable of. We got it, so that feels good. I was trying to do everything in my power to get it. I was frustrated with how things were going, but I’m just glad we got it.”

The question for Anderson is whether the run that gave him the milestone will be his last with the Broncos. The running back signed a four-year, $18 million with Denver in 2016, and he’s owed a base salary of $4.5 million over the next two seasons. But none of that money is guaranteed, leaving the Broncos with no financial penalty should they decide to move on from the 26-year-old.

“We’re all uncertain,” Anderson said while answering a question about coach Vance Joseph’s potential future with the team. “My guaranteed money is up, too. We are all uncertain. We’ll just see.”

In another milestone chase for the Broncos, wide receiver Demaryius Thomas narrowly missed his sixth straight season of 1,000 yards receiving. Thomas needed 108 yards Sunday and finished with six catches for 57 yards and a touchdown.