At age twenty-nine, Neacsu made her official debut for the 2008 Summer Olympics in Beijing, where she competed in the women's 800 metres. She ran in the fifth and final heat of the event, against six other athletes, including Morocco's Hasna Benhassi, who eventually won the bronze medal in the final. She finished the race in sixth place by nearly two seconds behind U.S. middle distance runner Hazel Clark-Riley, with a time of 2:03.03. Neacsu, however, failed to advance into the semi-finals, as she placed twenty-eighth overall, and was ranked farther below three mandatory slots for the next round.