Raphael Varane was forced off at half time with discomfort in his right leg, but Los Blancos rallied and got over the line through two goals in the second half.
Zidane, though, was keen to focus on the positives without confirmation of the defender's condition.
"I hope it's something small, but I can't tell you," Zidane said in his post-match press conference.
"Varane says it's a small thing and I hope that it is.
"A lot of things have happened to us, but today we've got three more points and we're going to fight until the end. We can.
"I'm not saying that we're going to win everything, but we're going to do everything we can to try to win."
"He did well," Zidane said of the Belgian No.7.
"Especially in that position, close to Karim [Benzema], I think he did very well."
Real Madrid's players have been close to their physical limit for quite some time now, but Zidane was happy with the fitness levels he saw on Saturday.
"Today we were very good physically and mentally," he said.
"We're playing every three days and these details are very important.
"We were very good physically today."