Real Madrid coach Zinedine Zidane admits his changes failed to come off after their 1-1 draw with Real Sociedad on Monday night.

Zidane switched to a back three at half time, with Cristian Portu's opening goal coming as a result of that change of formation.

"I changed it because I wasn't happy with our pressing," Zidane told the media at full time.

"It was those 10-15 minutes and we changed it again and we were better playing a 4-3-3.

"Our substitutes did well after coming on.

"If you've asked me and that's now three times, then yes, maybe," Zidane replied when asked whether his changes had harmed Real Madrid.

"We had to change things because, after an hour, the team was a bit tired. Sometimes we have to change things.

"In the end, you try to find things to change the dynamic."

The 1-1 draw was a disappointing result for Los Blancos heading into next Sunday's derby against Atletico Madrid. They are now five points behind their rivals in the table.

"We have to remain calm," Zidane insisted.

"We had a good game and we had three or four chances [to score].

"Patience, calm and rest. We were up against a team that creates chances against you.

"We have to carry on.

"It doesn't change the way we go into the derby. We have to go there to have a great game."