Bale, who scored one goal in nine appearances against Liverpool when he was at Tottenham Hotspur, last played for Real in the 5-0 La Liga win over Athletic Bilbao on Oct.
5 but Ancelotti said he was “fine”.
“The question is whether to deploy a player who is coming back from injury from the start,” Ancelotti told a news conference previewing the match at the Bernabeu. “I will decide tomorrow.”
Holders Real top the group with nine points from three matches and will secure a place in the knockout round with another victory over Liverpool, whom they outclassed 3-0 at Anfield last month.
Saturday’s 4-0 romp at Granada in La Liga was Real’s 11th consecutive win in all competitions and lifted them to the top of the standings after 10 matches.
Cristiano Ronaldo netted his 17th La Liga goal of the campaign and will have another chance on Tuesday to equal or surpass Raul’s Champions League scoring record of 71 goals.
Portugal forward Ronaldo, who set a scoring record for a single season of Europe’s elite club competition of 17 goals in 2013-14, is currently one behind his former Real team mate on 70.
“He (Ronaldo) is not thinking about Raul’s record, he is thinking about the team,” Ancelotti said.
“He could beat it tomorrow but it won’t be his last Champions League appearance,” added the Italian.
“I always have to talk about Cristiano and I already said that it’s tough to find new words. He is a fantastic player.”
Ancelotti, who helped end Real’s 12-year wait for a record-extending 10th European crown last season in his first term in charge, was asked about reports in Spain that he is poised to agree an extension to his contract, which expires at the end of the 2015-16 campaign.
“If the club is happy with me I want to carry on,” he said.
(Editing by Martyn Herman)