After spending time at VK Tielrode and Germinal Beerschot, Vertonghen moved to the Netherlands and signed a contract with the youth academy of Eredivisie side AFC Ajax.
He began as a midfielder but then became a regular at centre-back for Ajax.
During his time in the reserves, he became known for an incident in a 2006 KNVB Cup game against Cambuur Leeuwarden, his first home game at the Amsterdam Arena, where he scored a goal to put Ajax 3–0 up.
He had attempted a back pass to the Cambuur goalkeeper while a teammate was receiving treatment but instead the ball went into the goal.
Since it was  unintentional, Ajax allowed Cambuur to score a goal in return.
On 23 August 2006, Vertonghen made his first team debut in the Champions League third qualifying round against Copenhagen.
He made his first start and Eredivisie debut in a 6–0 win over Willem II at the Amsterdam Arena and would play another two matches for the first half of the season.
After spending time at VK Tielrode and Germinal Beerschot, Vertonghen moved to the Netherlands and signed a contract with the youth academy of Eredivisie side AFC Ajax. He began as a midfielder but then became a regular at centre-back for Ajax. During his time in the reserves, he became known for an incident in a 2006 KNVB Cup game against Cambuur Leeuwarden, his first home game at the Amsterdam Arena, where he scored a goal to put Ajax 3–0 up. He had attempted a back pass to the Cambuur goalkeeper while a teammate was receiving treatment but instead the ball went into the goal. Since it was  unintentional, Ajax allowed Cambuur to score a goal in return. On 23 August 2006, Vertonghen made his first team debut in the Champions League third qualifying round against Copenhagen. He made his first start and Eredivisie debut in a 6–0 win over Willem II at the Amsterdam Arena and would play another two matches for the first half of the season.
Jan Vertonghen