Smith had 36 yards on seven carries before leaving Thursday's 27-15 loss to Green Bay.
A league source told ProFootballTalk.com that Smith suffered a mild ankle sprain instead of the dreaded high ankle sprain that was feared on Thursday. A high ankle sprain would probably sideline Smith for weeks instead of the nine days before the Lions next game, a Dec. 4 date with New Orleans Saints.
Smith had sounded optimistic on Thursday.
"It wasn't that bad, it's just a matter of I couldn't cut," Smith said. "My X-ray came back negative. ... I think we've just got to do further tests."
If Smith is unable to play, Maurice Morris would likely replace him, with Keiland Williams getting extra work.
Jahvid Best is done for the season after the Lions announced Friday that he would be placed on injured reserve because of ongoing symptoms from a concussion.
The Associated Press contributed to this report.
