Spain's big two clash at the Bernabeu on Saturday evening and the Welshman has declared himself fit and ready if called upon by manager Rafael Benitez.
Bale has been struggling with a calf problem since last month; a recurrence of an injury which had sidelined him earlier in the season for nearly three weeks.
He has played in just seven of 15 matches for Madrid this season due to the ongoing problem, which saw him miss his country's friendly with the Netherlands last week.
However, he says he is ready to face Barcelona.
"I've been out with injuries for maybe six weeks now, so I haven't played as much as I would have liked," he told Real Madrid's official website.
"But I feel strong and fit going into this game. I am ready for the battle."