VEZZALI beat Ines BOUBAKRI (TUN) in a sudden-death play-off of extra time after a slow-scoring match in which they were locked 7-7 at the end of normal time.
She will now meet fellow Italian Arianna ERRIGO in the semifinals.
In the second semifinal, another Italy team member, Elisa DI FRANCISCA, takes on the Beijing 2008 silver medallist NAM Hyun Hee (KOR), meaning the top four women foilists in the world have reached the final stages of the London 2012 Olympic Games.
DI FRANCISCA staged a dramatic comeback in the round of 16 after trailing Carolin GOLUBYTSKYI (GER) 7-2. She then scored 11 of the next 12 hits, unintentionally wounding the German when her blade flicked under the mask to inflict a painful blow to the chin.
ERRIGO smoothed her path to the semis with impressive wins over Kamilla GAFURZIANOVA (RUS) 15-7 in the last 16 and Lee KIEFER (USA) 15-10 in the quarterfinals.
NAM's closest match came in the round of 16 when she traded hits to 7-7 with the experienced Aida MOHAMED (HUN), who was fourth in Beijing, before clinching the bout. She went on to beat Kanae IKEHATA (JPN) 15-6 in the quarters.
Picture: FIE photographer Serge Timacheff