Zinedine Zidane believes his substitutions made the difference as Real Madrid came from behind to defeat Sporting CP 2-1 in their Champions League opener.

The holders of the competition fell behind to Bruno Cesar's excellent strike two minutes into the second half, and with 67 minutes on the clock Zidane sent on Alvaro Morata and Lucas Vazquez.

The pair immediately added more energy but it was Cristiano Ronaldo who fired home the equaliser from a brilliant free-kick with one minute of normal time remaining.

Morata secured all three points when he headed home a cross from James Rodriguez – another substitute – in the 94th minute, and the French coach was pleased his decisions paid off.

"We are happy because we kept going until the end, we didn't give up. Sometimes you meet an opponent who play very well but our players were tremendous, they made an enormous effort and they got their just reward," said Zidane.

"It's a coach's job to make substitutions and we're happy that they paid off. You make substitutions in order to change the game and that's what happened today.

"The three substitutes all gave us something when they came on. I'm happy with all three.

"This is Real Madrid and we know we can always turn things around in a minute. We played a little better after conceding and we finally did it."

Zidane admitted his team came under serious pressure in the first half but was pleased with their fight in ensuring they came out on top.

"They took it to us, especially in the first period. After they scored we took more control of the ball," he continued. "I don't know if the result was fair or not, but it's clear we believed.

"It wasn't a perfect match; you never see a perfect match but the important thing was to win. Later we'll analyse things. There's nothing in particular to single out what I didn't like.

"We can play better, especially in the first half. There's two sides playing and they went to war with us. It's the Champions League; there's nothing easy in football, especially the Champions League."