After being left out of the squad for the La Liga match with Sevilla last weekend, the Wales international was included in the starting XI for the Copa del Rey contest, in which Los Blancos ran out 3-1 winners.
However, after twisting his ankle, Bale hobbled out of the match on 53 minutes. Afterwards Zidane provided an update on his condition.
"He's twisted his ankle a bit," said the Madrid coach, per Matt Dorman of Goal. "I don't think it's much but, as always, we'll see tomorrow. He couldn't go on."
Before the injury, the night looked like it might be a prosperous one for Bale, as he opened the scoring with a deflected shot. It had been a long time since the 30-year-old hit the back of the net for Madrid:
After Bale left the action, the home side were able to equalise through Alvaro Romero; an own goal from Juan Gongora and another from Brahim Diaz ensured Madrid progressed into the next round.
The outing was the first Madridistas have seen of Bale since the showdown with Getafe on January 4. In the 2019-20 season, he's only made nine La Liga starts for the club, with the forward once again struggling with fitness and illness issues.
Bale's absence from the squad against Sevilla prompted fresh transfer speculation about a January move for the player. In the summer, the former Tottenham Hotspur star came close to a move to Jiangsu Suning, before Madrid pulled out of a deal.
Bale's agent Jonathan Barnett has ruled out any midseason move, though, and has said he expects the Welshman to be at Madrid for a while yet:
With Eden Hazard injured and Karim Benzema only just returning from a layoff, Bale had an opportunity to nail down a spot in the XI with a strong performance. However, the latest in a long line of injury problems will do little to enhance his chances of game time before the end of the season.
Madrid are next in action on Sunday in La Liga, when they visit Real Valladolid. In light of the injury, it would be a surprise if Bale was involved in that contest.