Vos led off the final corner, but Bronzini was dragged into contention by her teammates Laura Trott and Peta Mullins, and launched herself to the line alongside the world number one.
Bronzini threw her arms in the air and Vos stretched out her hand in congratulations, but it was so close that at first the announcers weren’t sure who would get the verdict.
When the result was confirmed, Bronzini beamed with delight, relieved that she had made amends for her last appearance in London when her chances of an Olympic medal were ruined by a flat tyre.
"That felt so good," said Bronzini, a former world champion who celebrated her 31st birthday last Sunday. "Any time you beat Marianne in a sprint you know you’re going to win."
Twelve months ago it was Trott who snatched victory for Wiggle Honda, but this time the 22-year-old Londoner played a supporting role, aiding Bronzini’s last-lap bid for the line, an effort the Italian was swift to acknowledge after the race.
"In the middle of the race I asked my teammates to make it hard and put in attacks to take the sting from Vos," said Bronzini. "What I did today was because of the support of my team.
"I think we made her tired by attacking as a team. That was our tactic today, and in the end it was a great sprint into a headwind.
"She was ahead until 100 metres to go when I passed her, but she came back and I had to push hard in the final 50 and lunge for the line. The last time I was here for the Olympics it was not a good day, so this time I wanted to win badly. It is so amazing to win here in such a historic city and in front of these amazing buildings.
"I really like racing in the sun, and today was a beautiful day."
Vos thought she may have began her sprint too early, and could not make up for the mistake, but she was pleased with the second place finish. “Today Giorgia was faster on the line. I knew I couldn’t make any mistakes so it was always going to be close. At the end she was just very fast.
"It was so amazing to race here again, especially in such a great race," she added. "To be part of a criterium with all the world’s top riders was an amazing feeling."
Behind the two tearaway leaders, Lizzie Armitstead stole third place for Boels Dolmans from Eileen Roe of Starley Primal Pro Cycling as Trott took fifth ahead of her arch rival, Hannah Barnes of UnitedHealthcare Pro Cycling, last year’s runner-up.
Many had predicted Armitstead would be Vos’s closest rival, but the Briton admitted she was happy with third just a week after winning the Comonwealth Games road race gold in Glasgow.
"I had not really prepared for this because I’ve been concentrating on road races," said the 26-year-old from Yorkshire. "For me it was not about winning today but about having some fun."
|#||Rider Name (Country) Team||Result|
|1||Giorgia Bronzini (Ita)||0:46:46|
|2||Marrianne Vos (Ned)|
|3||Lizzie Armitstead (GBr)|
|4||Eileen Roe (GBr)|
|5||Laura Trott (Ned)|
|6||Hannah Barnes (GBr)|
|7||Tiffany Cromwell (Aus)||0:00:01|
|8||Grace Garner (GBr)|
|9||Nicola Juniper (GBr)|
|10||Abbie Dentus (GBr)||0:00:02|
|11||Katie Curtis (GBr)|
|12||Lauren Creamer (GBr)|
|13||Mel Lowther (GBr)|
|14||Harriet Owen (GBr)|
|15||Lydia Boylan (GBr)||0:00:04|
|16||Hayley Jones (GBr)|
|17||Gabriella Shaw (GBr)|
|18||Keira McVitty (GBr)|
|19||Laura Greenhalgh (GBr)|
|20||Nikki Harris (GBr)|
|21||Mary Costelloe (GBr)||0:00:05|
|22||Clemence Copie (GBr)|
|23||Jennifer Crouch (GBr)|
|24||Sophie Faulkner (GBr)|
|25||Elizabeth Holden (GBr)|
|26||Lucy Coldwell (GBr)|
|27||Sophie Lankford (GBr)|
|28||Rebecca Womersley (GBr)||0:00:06|
|29||Iona Sewell (GBr)|
|30||Rebecca Rimmington (GBr)|
|31||Lucy Chittenden (GBr)|
|32||Merce Pacios (GBr)|
|33||Cassie McGoldrick (GBr)|
|34||Hayley Simmonds (GBr)|
|35||Jessie Walker (GBr)|
|36||Abby Mae Parkinson (GBR)|
|37||Madeline Moore (GBr)||0:00:07|
|38||Lauren O'Brien (GBr)|
|39||Jo Tindley (GBr)|
|40||Penny Rowson (GBr)|
|41||Anna Christian (GBr)|
|42||Hannah Walker (GBr)||0:00:08|
|43||Brit Tate (GBr)|
|44||Clare Gillott (GBr)||0:00:09|
|45||Jennifer George (GBr)|
|46||Sarah Storey (GBr)|
|47||Ally Stacher (USA)|
|48||Karol-Ann Canuel (Can)||0:00:10|
|49||Tracy Best (GBr)|
|50||Amy Roberts (GBr)|
|51||Evgenia Ilyinskaya (GBr)||0:00:12|
|52||Maxine Filby (GBr)||0:00:15|
|53||Roxane Knetemann (Ned)||0:00:24|
|54||Emilia Fahlin (Swe)||0:00:28|
|55||Peta Mullins (Aus)|
|56||Jasmine Dotti (GBr)||0:01:06|
|57||Emily Collins (NZl)||0:01:55|
|58||Bethany Taylor (GBr)||- 2 laps|
|59||Tanya Griffiths (GBr)||- 4 laps|
|60||Sarah Piner (Irl)|
|61||Nicola Soden (GBr)|
|62||Nicole Oh (GBr)|
|63||Nicola Engelbach (GBr)|
|64||Ruby Chappell (GBr)|
|65||Hisayo Kaneko (GBr)|
|66||Fiona Guihen (Irl)|
|67||Tamala McGee (GBr)|
|68||Adel Tyson-Bloor (GBr)|
|69||Bella Leach (GBr)|
|70||Emma Towers (GBr)|
|71||Darrelle Parker (GBr)|
|72||Amy Gornall (GBr)|
|73||Laura Cheesman (GBr)|
|74||Sandra Mackay (GBr)|
|75||Hannah Ormesher (Irl)||- 5 laps|
|76||Emily Barnes (GBr)|
|77||Annabel Sill (GBr)|
|78||Lucy Harper (GBr)|
|79||Sarah Odell (GBr)|
|80||Julie Erskine (GBr)|
|81||Anna Marie Hughes (GBR)|
|82||Michelle Forster (GBr)||- 6 laps|
|83||Nichola Roberts (GBr)|