The Wales international winger, who moved to the Spanish capital from Tottenham for 100million euros last week, has only played 32 minutes of football this season due to injury.
That game-time arrived from the bench as Wales lost 3-0 to Serbia on Tuesday night but Bale has since trained alongside his new Madrid team-mates without any setbacks, allowing coach Carlo Ancelotti to promise him an appearance at El Madrigal.
The Italian told a press conference on Friday: "Bale will travel to Villarreal and will play.
"I'm not sure if he will start or come off the bench."
It had been mooted that Bale would slot in at left-back - his original position at Southampton and in his first years with Spurs - given injuries sustained by Marcelo and Fabio Coentrao on international duty, but Ancelotti has other ideas.
When asked about where he would field the 24-year-old, he added: "On the right-hand side [of attack]."
Los Blancos are not exactly desperate for their investment to come into the starting line-up and make an immediate impact, given they have won all three of their three opening Primera Division matches.
Ancelotti feels the Welshman will bring welcome "enthusiasm" to proceedings nevertheless.
"Bale came here without having a normal pre-season, but his condition is not bad," he added. "He will travel tomorrow, and he will play. He has no injuries, he is excited and very motivated.
"He's arrived full of enthusiasm and he is very happy to be at the team he wanted to join. He is a humble player who likes to be with his team-mates. He fits in well with the squad."
Defender Raphael Varane (knee) and Xabi Alonso (foot) are definitely missing for Madrid, while Villarreal are likely to be without struggling duo Bojan Jokic (hamstring) and Francisco Farinos (Achilles).
The Yellow Submarine - recently resurfaced following a year in the Segunda Division - are also perfect in the fledgling La Liga table having beaten Almeria, Valladolid and Osasuna.
Only three sides left the Madrigal victorious during Villarreal's season in exile but coach Marcelino knows sending Madrid packing is a slightly more daunting task than resisting the likes of Barcelona B and Ponferradina.
"Playing against Madrid is different," he told his club's official website. "But we always try to win and we will stand up to our rivals no matter who they are.
"We know it will be more difficult because of the quality of this opponent, but we will try to win.
"We will not make big changes - we have our weapons and we will go out and use them."