Messi has not scored in the league since September, although he recently spent two months on the sidelines with a hamstring injury.
The 26-year-old has seemingly been deployed in a deeper position since returning to action, but Ancelotti is unsure whether it is a permanent change.
"I don't know whether Messi has changed position," Ancelotti stated at a press conference.
"He has played well in recent matches and has shown that he is fit and has recovered well from his injury. He has not scored many goals, but he is still, as he always has been, very important for Barcelona."
Messi has scored 18 times this season.