The 23-year-old is already favourite to be crowned both European and World Player of the Year in the next couple of months.

Last season Ronaldo was a class apart from most of his peers, netting 42 goals to help United win the Premier League and Champions League double. But the Portugal ace is adamant he still has plenty of room to improve.

"Of course. If a player thinks that he already knows everything, he is dead," said Ronaldo in Marca.

"I still have a lot of aspects to polish up and many things to improve.

"I don't think my learning has finished yet and I am going to keep improving day by day until the end of my career, without doubt."

Ronaldo missed the start of this season after undergoing ankle surgery in the summer, but he is already back in the United team and scoring again.

The former Sporting Lisbon player admits he is still not back to full fitness, but hopes to be there once he gets a few more games under his belt.

He said: "I'm still not (totally recovered) but inside three of four games I will be at my best level physically and mentally. This year I couldn't take part in pre-season and this also affects things."

He added: "I know that it is difficult to do the same as last year or better, but I'm an ambitious person and I am hopeful that soon I am going to be better, as much physically as mentally.

"I'm calm, because I know that a person who is good one year needs to be the same the following year."

One of Ronaldo's crowning achievements last year was helping United win the Champions League, with the Portuguese scoring the opening goal of the final against Chelsea before the Red Devils went on to win in a penalty shoot-out.

Ronaldo is hoping for more of the same this season, although he admits he now wants to face either Spanish giants Real Madrid or Italian outfit Internazionale in the final.

The biggest transfer saga of this summer involved Madrid's pursuit of Ronaldo, while Inter are now coached by the winger's compatriot Jose Mourinho.

"I would like to face Real Madrid or Inter. I've never had the opportunity to play against Real Madrid or Inter and it would be a very nice experience," Ronaldo said.