Almatbouli's win will have been big news in his home town, where friends and family, including his five brothers, gathered in cafes to watch his bout live on television, and in the venue itself, where he was cheered by team-mates and supporters.
Almatbouli said: 'Everybody back home will be proud. With this achievement hopefully I can become a role model. Despite a difficult life I never stopped doing my sport and it is a dream to be here at an Olympic Games.'
Despite a difficult life I never stopped doing my sport and it is a dream to be here at an Olympic Games.Ihab Almatbouli
Meanwhile, Australia's world number two Damien Hooper pulled out a fantastic last round to beat American Marcus Browne 13-11. Trailing by a point heading into the last, Hooper poured in the punches and forced Browne to take a standing count.
Mongolia's former world silver medallist Tugstsogt Nyambayar looked like a potential medal contender at Fly Weight as he dispatched Azerbaijan's Elvin Mamishzada, himself a former world quarter-finalist, 18-11.
Algeria's Samir Brahimi poured in the punches in the final round as he came from behind to beat Australian teenager Jackson Woods. Woods led by three points after the first session but tired badly as the contest drew on.
Puerto Rican 17-year-old Jeyvier Cintron Ocasio edged past Oteng Oteng of Botswana 14-12 and there were also wins for Juliao Neto of Brazil and Egypt's Hesham Abdelaal.