Wayne Rooney believes playing alongside Cristiano Ronaldo was an 'education', and admits to being upset when the Portuguese star swapped Old Trafford for the Santiago Bernabeu.

Ronaldo and Rooney joined Manchester United only a year apart, with the former signing for the club in the summer 2003 and the latter completing a move the following season.

In the four years they spent together at the club, the forward duo formed a formidable understanding as United won three league titles and lifted the Champions League in May 2008.

But, a year later, Ronaldo was sold to Real Madrid in a record-breaking £80 million deal, and Rooney was forced to carry United's goalscoring burden.

And, says the England striker, he learned so much from Ronaldo, and has been impressed to see the 26-year-old hit even greater personal heights in Madrid.

"It was thrilling and an education to play alongside him," said Rooney.

"I was perhaps a little (upset) when he left, but I was also happy for him because he wanted to have other experiences: 87 goals in 80 games with Real Madrid seem like a good enough explanation to me, no?"

Do YOU want to write for GiveMeSport? Get started today by signing-up and submitting an article HERE: http://gms.to/writeforgms