The Eala-Ribera stunned the second-seeded Raina and Thombare, 6-2, 6-2 in the round of 16 match in Vitoria-Gasteiz in Spain.
The match ran for a little over an hour.
The Filipino-Spanish duo won a total of 51 points, compared to the 35 points won by Raina and Thombare.
Eala and Ribera also won 28 service points against the higher-seeded pair’s 19.
Raina is ranked 179th in doubles competition by the Women’s Tennis Association (WTA,) while Thombare is No. 192.
For her part, the 18-year-old Eala is rated 688th, while Ribera is the 532nd.
Up next for Eala and Bassols Ribera will be the quarterfinal match against Latvian Diana Marcinkevica and French Estelle Cascino on Thursday.
Eala is also set to have an uphill battle in the first round of the singles competition, where she will go head-to-head against Romanian Jaqueline Cristian.
Cristian is the fifth seed in the tournament and is currently 123rd in the WTA singles ranking, while Eala is currently sitting 258th.
