The 76ers are saying they don't know when Nerlens Noel will return to the court.

The rookie power forward was a late scratch from Monday's game against the San Antonio Spurs at the Wells Fargo Center. Noel was hurt Sunday when he was elbowed in the hip by Hollis Thompson during practice.

"It's day-to-day," coach Brett Brown said following Monday's 109-103 setback. "It kind of surprised me that he wasn't going to be able to go. He tested it, and he pulled himself [back] into practice [Sunday]. We sat him. He said let me go. So I respected it. "

Noel participated in Monday's pregame warmups, but wasn't physically able to play in the game. This marked the third game he missed this season.  The 6-foot-11, 217-pounder missed games against the Chicago Bulls (Nov. 7) and the Toronto Raptors (Nov. 9) with a sprained left ankle.

"I think the lesson for him and everybody is, you know, everybody in the NBA is injured," Brown said. "Everybody's injured. And watch how injured they are in April and March. But if you're really injured, and there are some problems, shame on me for trying to force feed it on the court.

"So we hope to not go a step forward and three steps backs, because that kid's moving in the right direction."

Noel is averaging 7.9 points, 6.5 rebounds, 1.57 steals and 1.29 blocks on the season. However, he has scored in double-figures in four of his past six games and is averaging 9.7 points while shooting 58 percent during that stretch.  The 20-year-old leads all rookies in rebounding, steals, blocks and field-goal percentage (47.6 percent).

"We are going to go overboard to make sure his health is as we preach," Brown said. "It's of Number One importance.

"And I expect him to be back soon, I don't know what that date means."

Follow and contact Inquirer 76ers beat writer Keith Pompey on Twitter @PompeyOnSixers and on Instagram at PompeyOnSixers