However, many Madrid fans won't be losing any sleep should the Welshman miss out as Real have thrived despite another injury-ravaged season for the world's second most expensive player.
"There has been no Real Madrid fan seen crying over Bale's injury," said an editorial in Madrid sports daily Marca this week.
"Bale's absence is a solution for Real Madrid, not a problem."
Some of Bale's obvious individual qualities have shone through in his four seasons since moving to Madrid for a then world record fee of just over 100 million euros ($107 million).
He scored more headed goals than anyone in Europe last season, still possesses electric pace and a deadly left foot.
Indeed, his role in winning two Champions Leagues in the past three seasons was rewarded with a massive new five-year contract reportedly worth £600,000 a week back in October.
However, the statistics show Madrid have benefited far more when coach Zinedine Zidane has balanced his side with less glamorous names to work within a more solid structure.
Bale's injuries have limited him to just 18 of Madrid's 31 La Liga games this season, in which the European champions have won 12, drawn five and lost once at Valencia.
By contrast, Lucas Vazquez -- who cost Madrid a meagre one million euros in 2015 -- has thrived in Bale's absence, winning in 22 of his 28 La Liga appearances this season.
In 13 games without Bale, Madrid's win percentage jumps from 67 to 85 percent.
- Squad gains -
Madrid go into the Clasico well set to deliver their first league title in five seasons and the first of Bale's career.
Real are three points clear of Barca and have a game in hand.
The massive difference between the sides so far this season has been the depth of Madrid's squad.
Whilst, Barca boss Luis Enrique has paid for rotating in shock defeats to Alaves, Celta Vigo, Deportivo la Coruna and Malaga, Real's reserves have at times delivered even better results than Zidane's first-choice XI.
The Frenchman made sweeping changes for three of Real's last four away league games at Eibar, Leganes and Sporting Gijon.
Despite Bale and Cristiano Ronaldo not even being included in the squad, Madrid won all three games.
However, the likes of Vazquez and Marco Asensio have not just proven themselves against La Liga's lesser lights.
All of Madrid's four goals in Wednesday's thrilling 4-2 extra time Champions League win over Bayern Munich came after Vasquez and Asensio had replaced Karim Benzema and Isco.
Asensio, 21, confirmed his status as one of Europe's most exciting young talents with a virtuoso solo goal to round off the scoring after Ronaldo's hat-trick.
Previous Madrid coaches such as Carlo Ancelotti and Rafael Benitez have complained the stars like Bale have to play in the biggest games by president Florentino Perez's decree.
However, Zidane has shown his insistence to put collective glory ahead of what is best for Madrid's marketing campaigns.
Despite costing 80 million euros and being top scorer at the 2014 World Cup, James Rodriguez has been completely marginalised for the far more pragmatic, destructive characteristics of Casemiro in the Madrid midfield.
With Madrid one knockout blow away from ending Barca's domination of La Liga in recent years, Zidane has a big decision to make should Bale prove his fitness ahead of Sunday's showdown.