(CNN) -- Cristiano Ronaldo has consistently been linked with a move back to Manchester United -- but Real Madrid star Mesut Ozil insists his club must hold onto the player if it is to challenge at the very top. 

Ronaldo, who left United for Real in a world record $130 million deal in 2009, has been the subject of much speculation in recent months. 

The 28-year-old has scored 201 goals in 199 appearances for Real and club president Florentino Perez recently stated that he expected Ronaldo to finish his career in the Spanish capital. 

But the speculation refuses to disappear -- leaving Ozil hoping his Portuguese teammate stays put. 

"Cristiano Ronaldo is very important to the team, just look at all the goals he has scored in the past few seasons," he told CNN. 

"He's a great person off the field. I hope he can stay here for a long time because he can help us win important titles." 

The loss of Ronaldo would be a huge blow to a Real side hoping to snatch the league title back from Barcelona and win its first Champions League crown since 2002. 

Real has lost out at the semifinal stage in each of the past three seasons with Borussia Dortmund the last team to put paid to the Spanish club's dream of a 10th triumph in the competition. 

"We have come very close to winning the Champions League in the past few years and that leaves a very bitter taste in the mouth," Ozil revealed. 
How many goals has Cristiano Ronaldo scored?
How old is he?
How many appearances?
Where might he be moving back to?
What club is he a part of at the moment?
Do they want him to leave?
What year did he make a deal with Real?
For how much money?
What country is Real from?
Do they think he is a bad guy in day to day life?
Who are they wanting to get the title from?
What would they win?
When was the last that they won it?
What stage have they lost at?
Was it just the last season?
How many seasons?
Have they ever got close to winning the Championship?
201
201
28
28-year-old
199
199 appearances
Manchester United
Manchester United
Real
Real
no
Cristiano Ronaldo is very important to the team
2009
 2009
$130 million
$130 million
Spain
the Spanish club
no
He's a great person off the field
Barcelona
snatch the league title back from Barcelona
the Champions League crown
Champions League crown
2002
 since 2002
semifinal
lost out at the semifinal stage
no
in each of the past three seasons
three
three seasons
yes
We have come very close to winning the Champions League