Lizzie Armitstead finished eighth on the opening stage of the Giro Rosa as Girogia Bronzini won a sprint finish.
Britain's world champion, who started the day six seconds off the pace after Friday's prologue, is sixth, 14 seconds behind race leader Megan Guarnier.
American Guarnier finished second on the stage to pick up a six-second time bonus and take the overall race lead.
Molly Weaver lost 41 seconds and is now 52 seconds back while fellow Briton Emma Pooley is 77 seconds adrift.
Sunday's second stage from Tarcento to Montenars features an uphill finish.
The nine-stage race finishes on Sunday, 10 July.
Stage one result:
1. Giorgia Bronzini (Ita/Wiggle High5) 2hrs 38mins 22secs
2. Megan Guarnier (US/Boels Dolmans) Same time
3. Rasa Leleivyte (Ltu/Vai Aromitalia Vaiano)
4. Katarzyna Niewiadoma (Pol/Raboliv)
5. Claudia Lichtenberg (Ger/Lotto-Soudal Ladies)
8. Lizzie Armitstead (GB/Boels Dolmans) +5secs
34. Molly Weaver (GB/Liv-Plantur) +41secs
44 Emma Pooley (GB/Lotto-Soudal Ladies) +1min 03secs
General classification after stage one:
1. Megan Guarnier (US/Boels Dolmans) 2hrs 40mins 42secs
2. Katarzyna Niewiadoma (Pol/Raboliv) +8secs
3. Giorgia Bronzini (Ita/Wiggle High5) Same time
4. Rasa Leleivyte (Ltu/Vai Aromitalia Vaiano) +13secs
5. Evelyn Stevens (US/Boels Dolmans) +14secs
6. Lizzie Armitstead (GB/Boels Dolmans) Same time
17. Molly Weaver (GB Liv-Plantur +52secs
39. Emma Pooley (GB/Lotto Soudal Ladies) +1min 17secs