The former Paris Saint-Germain coach says that the Welshman will feature in some capacity, while adding that Iker Casillas will start in Tuesday's Champions League game
The Welshman joined Los Blancos from Tottenham for a world-record €100 million (£86m) transfer fee and is all set for his first Madrid appearance since returning from international duty.
The former Paris Saint-Germain coach says that Bale will play some part of the game but did not disclose whether or not the 24-year-old would start.
"Bale will travel to Villarreal and will play, although I don't know if he'll start or come off the bench," Ancelotti said at a press conference.
"Bale and Cristiano Ronaldo are two excellent players and I have no doubt that they will improve the team together.
"What I like the most about Bale? His motivation and his desire to make an impact here at Madrid. He is very happy and humble."
Ancelotti then went on to discuss the situation of Iker Casillas and revealed that the goalkeeper will feature from the start against Galatasaray in midweek.
"On Tuesday, Iker will play from the start, so everybody is calm," he added.
"It might be an option that Diego Lopez plays in La Liga and Casillas in the Copa del Rey."