In what's been an impressive debut at the Italian Grand Tour so far, Wiebes beat out Emma Norsgaard (Movistar) who finished second and Maria Vittoria Sperotto (A.R Monex) who settled for third as she managed to avoid a crash in the final five kilometres which involved multiple Team BikeExchange riders including Australians Amanda Spratt and Grace Brown.
Anna van der Breggen (SD Worx) again finished the race in the lead for the maglia rosa as the rankings remained unchanged.
Wiebes praised Rivera for putting her in the best position to win the day as she laughed off the prospect of replicating Marianne Vos' 30 stage victories at the race in the future.
“It was a really fast stage today and a messy sprint," Wiebes said after the stage. "But Coryn came at the perfect moment to bring me up to speed, and I could go all out to the finish."
“What Marianne did is amazing. I hope I can also go for the 30, but it is a really long way. We will see.”
A reduced peloton began the 130 kilometre course in San Vendemiano after teams Bizkaia-Durango and TIBICO-Silicon Valley Bank didn't start, forced to withdraw due to positive COVID-19 cases within their camps.
Multiple early attacks were unsuccessful until Anastasia Carbonara (Born to Win G20 Ambedo) broke away following the intermediate sprint as teammate Natalya Studenikina and Girogia Vettorello (Top Girls Fassa Bortolo) gave chase.
The trio built a gap of as much as three minutes and 15 seconds on the peloton with 50 kilometres to go, the peloton led by DSM and Movistar forced to work hard to eventually reel them in 6 kilometres from the finish.
With Team BikeExchange's hopes for the win dashed after riders Spratt, Brown, Janneke Ensing and Georgia Williams all crashed, Movistar led the bunch into the final sprint with Aude Biannic positioning herself to lead out Norsgaard.
DSM got in formation on Norsgaard's wheel and Rivera seized her chance, accelerating with 500 metres left out of the final turn to launch Wiebes through to the line for the victory.
Watch the highlights from the Giro d'Italia Donne on SBS from 3:30pm weekends or 4pm weekdays (July 3-12) or available earlier via SBS On Demand and the Cycling Central website.