(CNN) -- To the casual observer, Cristiano Ronaldo doesn't look like a man that feels pressure.
He is the driving force behind one of the world's biggest football clubs, Real Madrid, and reached 100 goals for Los Blancos faster than any other player in the Spanish champion's 111-year history.
But the Portugal star admits that, behind the bravado and on-field posturing, he and his teammates are feeling the strain of the expectation that surrounds the Madrid club.
Real's stuttering start to the season leaves them 18 points adrift of Spanish First Division leaders and archrivals Barcelona, with the club's fans now demanding coach Jose Mourinho lead Los Blancos to a record 10th triumph in Europe's premier club competition by way of compensation.
Real must overcome Manchester United in their last 16 clash if they are to win the European Champions League for the first time in 11 years -- a tie which will see Ronaldo return to the club where he announced himself as a world-class talent before leaving for Madrid in 2009 in a deal worth $129 million.
"I've been here for three-and-a-half years now," the 27-year-old told FIFA's official website. "Everyone involved is totally focused on winning the club's 10th European Cup. That creates a certain amount of anxiety, which can be felt at all times.
"The pressure is too great and that sometimes can affect us. But we have to try and rise above it and not let what people say get to us, particularly the media, as Real Madrid get spoken about every day.
"Every Madridista wants that 1oth European Cup -- we're more than aware of that. Last season we fell just short, which was very frustrating.
"Fortunately we've got the opportunity to set the record straight this year, though the fact we face Manchester United next makes it more difficult. It's not going to be easy and I reckon the odds are about 50-50, but I'm still very confident."
However, the worry for Spanish champions Real is that their team has been relatively inconsistent this season. While Barca have notched up a record 18 wins from the same amount of games during the current campaign, Mourinho's team have lost four and drawn four of their first 19 matches.
The crowd at the 85,000-seater Santiago Bernabeu stadium have targeted their frustrations at Mourinho -- a Champions League winner with both Porto and Inter Milan -- and Ronaldo.
"We haven't started the championship very well for sure," Ronaldo continued. "We know that La Liga's an uphill struggle for us now, but nothing's impossible in football. We're going to work hard, win games and see what happens.
He added: "I'm able to respect those who criticize me, because I know they've got the wrong idea about me. People who know me and those who've played alongside me know what kind of a guy I am. Those who don't know me can say and think whatever they want."
Ronaldo's return to United, who are currently leading the English Premier League table, has led many to reflect on the six successful years he spent in Manchester, winning the Champions League and being named World Player of the Year in 2008.
United manager Alex Ferguson admitted recently he would like to see Ronaldo return to Old Trafford, but the Madeira-born striker has moved to quell talk of an imminent move by saying he wishes to see out the remainder of his contract at Real, which expires in 2015.
"I want to see out my contract at Real Madrid; I'm very clear about that," he said. "After that, well, I don't know what'll happen in the future."
And head of February's contest between Real and United, Ronaldo is confidence his current club can overcome his former employers.
"No team's unbeatable, but when we're at our best we're a really good side. Manchester United have started the English championship race very well and are a long way ahead of the rest.
"But still, if we play the way we're capable of, we can beat them. To do that we need to pull together and play as a team, like we've done in so many matches before."