Ronaldo became Manchester United’s first Portuguese player when he signed before the 2003–04 season. His transfer fee of £12.24 million made him, at the time, the most expensive teenager in English football history. Although he requested the number 28, his number at Sporting, he received the number 7 shirt, which had previously been worn by such United players as George Best, Eric Cantona and David Beckham. Wearing the number 7 became an extra source of motivation for Ronaldo. A key element in his development during his time in England proved to be his manager, Alex Ferguson, of whom he later said, “He’s been my father in sport, one of the most important and influential factors in my career.”
Ronaldo made his debut in the Premier League in a 4–0 home victory over Bolton Wanderers on 16 August 2003, receiving a standing ovation when he came on as a 60th-minute substitute for Nicky Butt. His performance earned praise from George Best, who hailed it as “undoubtedly the most exciting debut” he had ever seen. Ronaldo scored his first goal for Manchester United with a free-kick in a 3–0 win over Portsmouth on 1 November. Three other league goals followed in the second half of the campaign, the last of which came against Aston Villa on the final day of the season, a match in which he also received his first red card. Ronaldo ended his first season in English football by scoring the opening goal in United’s 3–0 victory over Millwall in the FA Cup final, earning his first trophy.
At the start of 2005, Ronaldo played two of his best matches of the 2004–05 season, producing a goal and an assist against Aston Villa and scoring twice against rivals Arsenal. He played the full 120 minutes of the decisive match against Arsenal in the FA Cup final, which ended in a goalless draw, and scored his attempt in the lost penalty shoot-out. He scored Manchester United’s 1000th Premier League goal on 29 October, their only strike in a 4–1 loss to Middlesbrough. Midway through the season, in November, he signed a new contract which extended his previous deal by two years to 2010. Ronaldo won his second trophy in English football, the Football League Cup, after scoring the third goal in United’s 4–0 final victory over Wigan Athletic.
During his third season in England, Ronaldo was involved in several incidents. He had a one-match ban imposed on him by UEFA for a “one-fingered gesture” towards Benfica fans, and was sent off in the Manchester derby (a 3–1 defeat) for kicking Manchester City’s former United player Andy Cole. Ronaldo clashed with a teammate, striker Ruud van Nistelrooy, who took offence at the winger’s showboating style of play. Following the 2006 FIFA World Cup, in which he was involved in an incident where club teammate Wayne Rooney was sent off, Ronaldo publicly asked for a transfer, lamenting the lack of support he felt he had received from the club over the incident. United, however, denied the possibility of him leaving the club.
Although his World Cup altercation with Rooney resulted in Ronaldo being booed throughout the 2006–07 season, it proved to be his breakout year, as he broke the 20-goal barrier for the first time and won his first Premier League title. An important factor in this success was his one-to-one training by first-team coach René Meulensteen, who taught him to make himself more unpredictable, improve his teamwork, call for the ball, and capitalise on goalscoring opportunities rather than waiting for the chance to score the aesthetically pleasing goals for which he was already known. He scored three consecutive braces at the end of December, against Aston Villa (a victory that put United on top of the league), Wigan Athletic and Reading. Ronaldo was named the Premier League Player of the Month in November and December, becoming only the third player to receive consecutive honours.