DALLAS – The day after the Dallas Mavericks played the Los Angeles Lakers last week, Dennis Smith Jr. woke up and felt some tightness in the middle of his back.

Smith hasn’t played in a game since then and is currently listed as day-to-day.

“I don’t know when it happened,” Smith said prior to Sunday’s game against the Golden State Warriors. “It just got sore on me.

“I was feeling great going into (the Jan. 7 game against the Lakes), and when I woke up the next morning it was worse.”

Smith, 21, then playfully said: “I’m getting old. That’s all it is. That’s what happens with old age. Father Time is undefeated.”

Smith has missed the past three games, including Sunday’s 119-114 loss to the Warriors.

“He’s doing better,” coach Rick Carlisle said. “He’s had some back tightness from time to time.

“Part of it might be his body makeup, the fact that he is so put together. But he’s doing better and we’re hoping that can be back at practice this week.”