After the win in the 85 kg weightlifting tournament of 2001 Brisbane Goodwill Games in Australia, he established himself as prominent part of the world elite of weightlifters. He became part of the extended men's national team on February 11, 2001, and made his debut at the European Men's Championship in
Trenčín, Slovakia, winning bronze medal in the snatch, though failed to achieve a successful C&J attempt and posted a zero total. Later in 2001 he also made a debut at the 2001 World Championship in Antalya, Turkey, winning his first total bronze medal in the 85 kg category. In 2002 he won silver medal at the European Championship in Antalya, Turkey, in the 94 kg category. Later in the same year, Dobrev also became second at the World Championship in Warsaw, Poland. In 2003 he managed to win the gold medals both at the European Championship in Loutraki, Greece and the World Championship in Vancouver, Canada. His undefeated run continued in 2004, when he first won the European Championship in Kiev, Ukraine in April and then in August he peaked throughout his career winning the Olympic gold in Athens 2004 Olympic games
middle heavyweight class. The following year in
Doha, Qatar, he managed for bronze at the World Championships, which accounted for his last eight medal on a senior level. Milen Dobrev collected 4 gold, 2 silver and 2 bronze medals out of 10 major senior competitions in which he took part throughout his career. He was the first Bulgarian to win an Olympic title in weightlifting as a member of a team from Plovdiv (Maritsa-Olimp). Milen Dobrev has been an honorary citizen of Plovdiv since 2004. On April 20, 2005, at a ceremony in the Greek Embassy in Sofia, Bulgaria, he was also named honorary citizen of Athens, Greece. ==Death==