Portugal coach Carlos Queiroz has detailed how Real Madrid star Cristiano Ronaldo perfected his amazing free-kick ability.

Former Manchester United assistant manager Queiroz recalls hours spent on the training ground working with Ronaldo after coming to him with ideas of changing the technique of free-kick taking.

Queiroz told the Daily Mail: "I have always spent time with players on free-kicks but with Ronaldo we worked for days and days.

"I have learned something about technique from all the best ones, like Zidane and Krasimir Balakov, so at Manchester United we put that into Ronaldo, the details, the mechanics of their movement, how they position their bodies.

"Then I did my own study of biomechanics, I looked at the great free-kick takers like Michel Platini, the position of the chin, the arms, we introduced fine details, one step 20 centimetres to the left see what happens, position the feet here, the knee like this."

Then the hard work began.

"We practised every day, but the information will only get you so far. Beyond that, you need to have a genius with you to make it work, to give you the answers. All the rest is down to the capacity of the player to try the new ideas until he is efficient.

"I remember when we got to the Champions League final in 2008 against Chelsea. As usual I stayed with Ronaldo on the training field to sort the set-pieces with him. It was a new ball, a different ball for that match and our first day was a disaster.

"He could not get one free-kick between the posts, nothing was correct; it went up, it went left, it went right, never on target. So then we started on the details: stand to the right, to the left, put the standing foot there, strike it like this, inside the foot, outside the foot.

"After two days, still nothing, but after three days it started to fly how we wanted. Air distribution in all balls is different and that one was a nightmare to work out, but the important thing is that Ronaldo never quit. Not after two whole days with no success."