Despite her inexperience over the distance, Gidey was expected to chase a world record of 2:14:04 on debut and was on 2:14:10 pace through 30km.
But it was her compatriot Beriso who kicked on with 10km remaining, producing a stunning time of 2:14:58, the third fastest of all time, with Gidey holding on for second in 2:16:49, the fastest debut ever by a woman.
“I am more than happy. Conditions were perfect for me,” Beriso said, with Briton Paula Radcliffe’s 2003 London time of 2:15:25, a world record which stood for 16 years, now fourth on the all-time list.
There was another surprise in the men’s race, with runners capitalising on near-perfect conditions, as Kenya’s Kelvin Kiptum stormed to victory in a sensational 2:01:53 to land the fastest men’s debut in history.
Kiptum turned on the afterburners with less than 10km remaining to negative split with a 60:15 second half, including an astonishing 28:04 10km split from 30-40km.
Kiptum is just the third man to ever break 2:02 behind the legendary Eliud Kipchoge (2:01:09) and Kenenisa Bekele (2:01:41).
Famed for its fast, flat course, the weather was also kind to those in Valencia, who enjoyed temperatures of 9-10c with barely a gust across the two-and-a-bit hours of racing.
Gabriel Geay (2:03:00) second, Alexander Mutiso (2:03:29) third and Tamirat Tola (2:03:40) fourth, all broke 2:04 in the men’s race, while Sheila Chepkirui (2:17:29) was third and among seven women to break 2:19.
There was also an Australian record for 45-year-old Sinead Diver who clocked 2:21:34 to finish 12th.