Soccer's richest club by income, who like champions Barca have a perfect nine points from three matches, splashed a record 100 million euros (USD 133 million) to secure Bale's services and he could make his debut at promoted Villarreal in Saturday's late kickoff (2000 GMT). (Agencies)
The 24-year-old winger played the final half hour of Wales's 3-0 World Cup qualification defeat at home to Serbia on Tuesday, his first competitive action since July, and coach Chris Coleman warned afterwards it would be unwise for him to play a full match this weekend considering his relative lack of fitness.
After arriving in the Spanish capital on Wednesday, Bale had his first workout with his new team mates and although Real have a number of players injured, coach Carlo Ancelotti is unlikely to deploy him from the start at the Madrigal.
Portugal winger Cristiano Ronaldo, Spain playmaker Isco and Brazil fullback Marcelo all returned from international duty with problems of varying degrees of seriousness.
Ronaldo and Isco trained apart from the rest of the squad on Wednesday, while Marcelo had treatment from medical staff along with long-term absentee Xabi Alonso.
Villarreal, along with Atletico Madrid the only other team to win their opening three games, are eager to test themselves against opponents of Real's calibre after spending a year in the second division last term.
Under coach Marcelino they have shown real attacking flair and their performances so far this term suggest they are more likely to be challenging for a place in Europe than flirting with relegation come the end of the campaign.
"It's a chance to show that we can compete with anyone and that we can fight against a team like Madrid," captain Bruno Soriano told a news conference on Wednesday.
"Last year, we were dreaming about playing these teams and now the opportunity has arrived and we want to put in a great performance," the midfielder added.
Soccer's richest club by income, who like champions Barca have a perfect nine points from three matches, splashed a record 100 million euros (USD 133 million) to secure Bale's services and he could make his debut at promoted Villarreal in Saturday's late kickoff (2000 GMT).