Sena's sporting debut came as the youngest member of the Italian shooting team (aged 19), when she qualified only for the women's 10 m air rifle at the 2004 Summer Olympics in Athens. She had registered a minimum qualifying score of 395 from her top finish at the European Junior Championships in Győr, Hungary, to fill out a quota place for the Games, after the Italian Union of Rifle Shooting (UITS) decided to exchange a spot in the air pistol, won by Caterina Padovan at the World Championships in Lahti, Finland, two years earlier, with the air rifle. Among the less experienced in the field, Sena demonstrated her best ability to score 390 out of a possible 400 points in the qualifying phase, which was enough for her to finish in thirty-second out of forty-four shooters.