Asensio had been linked with a move away from Real during the transfer window but nothing materialised and he has only managed 17 minutes of on-field action this season.
Ancelotti overlooked the Spanish midfielder, with Dani Carvajal preferred to replace Lucas Vazquez who was injured in the 71st minute.
Asensio didnt try to hide his frustration, throwing his bib in disgust and booting a water bottle on the sidelines.
Despite that petulant and public act, Ancelotti said he understood the reaction fully and didnt condemn his player.
“We were preparing if we didn’t make it 2-1 to put Mariano and Asensio in,” he said.
“Lucas has been injured, and we only had one window, and I didn’t think about making that change.
“If he is angry, I agree with him. It’s normal, it means you want to play, feel important.
“In this period, he has been the most affected player in the squad and I take that into account.
“I totally agree with his anger, nothing happens.”
Los Blancos were forced to come from behind for their win, with Vedat Muriqi putting Mallorca ahead in the 35th minute.
Federico Valverde scored a spectacular equaliser in the fourth minute of first-half stoppage time before goals from Vinicius Junior, Rodrygo and Antonio Rudiger sealed the points.