Southpaw Blain was from 1993 to 1996 four times a French junior champion and 1997 to 2004 eight consecutive time French champion in the senior: 1997 and 1998 he won the title in the lightweight, from 1999 in the light welterweight. Blain 1996 took part in the Junior World Championships in Havana and retired there in the lightweight class in the quarterfinals of. At the 1999 World Championships in Houston, he took second place after a final defeat against the Uzbeks Mahamadkadir Abdullayev.
In 2000 he reached at the European Championships in Tampere, a third place and then took on France at the Olympic Games in Sydney in part. He retired from there, however, already in the first fight against the Cubans Diógenes Luna.
The European Championships in 2002 in Perm, he finished in second place. His greatest success as an amateur boxer he succeeded the following year, at the 2003 World Championships in Bangkok, when he was among other things the Cubans and Luna in the final controversial Alexander Maletin hit from Russia and amateur world champion in the light welterweight division.
In 2004, he took another third place at the European Championships in Pula. At the Olympic Games in Athens, he was less successful. Although he struck again Maletin, before he lost in the quarterfinals to eventual champion Manus Boonjumnong.
In 2004, Blain turned professional and signed with Spotlight Boxing in Germany. He did the same in his pro debut against an opponent with a low KO ratio to the ground, suggesting suggesting that he has rather poor slave capabilities. His other fights he won, but had little clout.
In April 2009, he punched the interime World Cup WBO light welterweight against Lamont Peterson ( 26-0 ), but this was subject prematurely. In November 2011, he lost the battle for the WBO Championship against Serhiy Fedchenko (28-1 ).