In 2004, El-Masri became a member of SG Neukölln swimming club in Berlin, and also, trained for the German national team. However, he decided to compete instead for the Syrian Olympic team at the 2004 Summer Olympics in Athens. He qualified for the men's 50 m freestyle event, and swam in the eighth heat against four other competitors including Croatia's Duje Draganja, who eventually won the silver medal in this event. El-Masri finished in fourth place of his assigned heat, with an impressive time of 22.58 seconds. He nearly missed out of the semi-final rounds, as he placed eighteenth in the overall rankings, tying his position with two-time Olympic champion Alexander Popov of Russia, and Johan Kenkhuis of the Netherlands.