Ancelotti, who viewed Beckham as a possible alternative to Andrea Pirlo as a deep-set playmaker before he arrived on loan from Los Angeles Galaxy, has the chance to test out his theory against Serie A's bottom club with Pirlo suspended.
However, he is wary of embarking on tactical experiments with a player in such good form.
"Beckham can play in a central position but (Mathieu) Flamini can (too) and that's why I tried it," Ancelotti was quoted as saying by La Gazzetta dello Sport after Wednesday's 2-2 draw at Glasgow Rangers in a friendly.
"Beckham has found a good equilibrium on the centre-right and I think it's best not to move him."
Forward Adriano is serving the last game of a three-match ban for throwing a punch against Sampdoria last month but Dejan Stankovic is being tipped to play after coming off with a knock in Sunday's 1-1 draw with Torino.
Last season's runners-up AS Roma, who are sixth, entertain fourth-placed Genoa on Sunday in a match between rivals for a Champions League qualification slot.
