After signing for Manchester United, he was unable to play for the senior team immediately because he was ineligible for a work permit. Due to these legal issues, Dong was loaned out to get first-team experience with Belgian First Division side Royal Antwerp where the employment laws were less strict. In his first season, he scored one goal in nine appearances as he began to get used to his new environment. His second season began more promisingly, finding the net in six of his first seven appearances of the season, all as a substitute off the bench. However, disrupted by injury and international duty, his form fell away in the latter half of the season as he finished with seven goals in 22 appearances in all competitions. At the beginning of the 2005–06 season, he was called up to join Manchester United on their pre-season tour and made his unofficial debut for the club in a friendly match in Hong Kong, scoring a goal in a 2–0 win.