It took just one season for Dinesh Karthik to transform from an obscure second-choice wicketkeeper for Tamil Nadu to a serious contender for a berth in the Indian squad. As a 17-year-old playing his first season in 2002, he showed glimpses of his batting talent but his wicketkeeping wasn't up to scratch, resulting in him being dropped for the Ranji Trophy knockout matches. However, his impressive showing in the Under-19 World Cup in Dhaka - including a whirlwind 70 in a must-win game against Sri Lanka - two vital hundreds in the Ranji Trophy knock-out and an improved showing behind the stumps resulted in him emerging as a contender for the national squad. He was picked in the Indian one-day squad, as replacement for Parthiv Patel, in August 2004, and made his debut in a NatWest Challenge game against England where he pulled off a superb stumping.
Shortly afterwards, he was called up to make his Test debut against Australia in the fourth Test at Mumbai. After managing just one fifty in ten Tests, he was axed in favour of the flamboyant Mahendra Singh Dhoni but he returned for India's tour to South Africa towards the end of 2006. He cemented his place in both Tests and ODIs and was chosen for the Bangladesh tour, India's first assignment after the forgettable World Cup, as a specialist Test opener. He scored his maiden Test ton in the second Test in Dhaka. Soon, though, Dhoni became irreplaceable and he got to play for India only when Dhoni rested. On one such occasion, in the 2008 tour of Sri Lanka, he was ordinary behind the stumps. He did have a good season in domestic cricket in 2008-09, though, keeping in tact his status of second-choice keeper, ahead of Parthiv. He scored three centuries in Ranji Trophy and captained Tamil Nadu through to the semi-final, and followed it up with two centuries in two Duleep Trophy matches. That earned him a comeback to all three Indian squads for the tour of New Zealand.