Following his world-record transfer from Tottenham, the Wales international is expected to be involved for Carlo Ancelotti's side, having featured for his country against Serbia on Tuesday.
The 24-year-old could even line-up at full back after Marcelo and Fabio Coentrao both suffered injuries during the international break.
Bale has admitted he might not be fully fit, but insisted he would be happy to play any role his manager needs him to on Saturday.
"We have to wait until the match day to see whether I'm picked or not," he said. "But hopefully I can get my fitness up straight away and get a place in the team.
"I have spoken to the boss about where I'm best on the pitch but I will play anywhere I'm asked."
Both sides have started the season with three wins out of three, but with Madrid dominating their opponents in recent meetings, they will be favourites to maintain their winning start.
Real have won 17 of their 26 meetings, and have not lost any of their last six encounters.
Villarreal only lost seven games on the way to a second-place finish and automatic promotion from the Segunda Division last season and they have started the new campaign well.
The Estadio el Madrigal has been a tough place for teams to visit in the past 12 months with only three sides having left with all three points, and captain Bruno Soriano remains confident they can surprise Real.
"It's a chance to show that we can compete with anyone and that we can fight against a team like Madrid," he said.
"Last year, we were dreaming about playing these teams and now the opportunity has arrived and we want to put in a great performance.
"Personally I prefer it if an opponent is at full strength and that the best come so we can take them on.
"Although even if Madrid has some players out, I am sure they will have the same level of quality."
Xabi Alonso (foot) and Raphael Varane (knee) will definitely be missing for Madrid, however Cristiano Ronaldo and Isco are expected to be available having taken part in training on Thursday.
Bojan Jokic (hamstring) and Francisco Farinos (Achilles) are doubts for the hosts having already missed the opening matches of the season.
