In 2000, Raina decided to play cricket and subsequently moved from his hometown Muradnagar, Ghaziabad, Uttar Pradesh (near New Delhi) to Lucknow, to attend the Guru Gobind Singh Sports College, Lucknow.He rose to become the captain of the Uttar Pradesh U-16s and came to prominence amongst Indian selectors in 2002, when he was selected at the age of 15 and a half years for the U-19 tour to England, where he made a pair of half-centuries in the U-19 Test matches. He toured Sri Lanka later that year with the U-17 team. He made his Ranji Trophy debut for Uttar Pradesh against Assam in February 2003 at the age of 16, but did not play another match until the following season. In late 2003, he toured Pakistan for the U-19 Asian ODI Championship before being selected for the 2004 U-19 World Cup, where he scored three half-centuries, including a 90 scored off only 38 balls. He was then awarded a Border-Gavaskar scholarship to train at the Australian Cricket Academy and in early 2005, he made his first-class limited overs debut, and scored 645 runs that season at an average of 53.75.