INDIAN WELLS, CA, USA - Two American wildcards made a statement in the second round of the Oracle Challenger Series event at Indian Wells on Thursday, as Danielle Collins and Caroline Dolehide each scored upset victories over Top 100 opposition to reach the quarterfinals.

Collins, who's already clinched a wildcard into the BNP Paribas Open by virtue of winning Newport Beach Challenger and her performance this week, bundled top seed and World No.56 Magda Linette out of the tournament from a set down, 5-7, 7-6(0), 6-4. 

Later in the day, 19-year-old World No.173 Dolehide overcame 13 double faults to oust No.3 seed and World No.69 Hsieh Su-wei in two tiebreaks, 7-6(5), 7-6(5). 

"Being able to play in Oracle events and having these Challenger Series, it’s just awesome being able to stay in the [United] States," Collins told the tournament website.

"[I'm] very grateful that Oracle has stepped up and is putting on more awesome events.”

Switzerland's Viktorija Golubic also scored an upset over a seeded player on Thursday, as she took out Chinese No.8 seed Duan Ying-ying, 7-6(4), 6-3.

The final player to advance to the last eight was Italy's Sara Errani, who defeated American Kristie Ahn by winning the last eight games, 6-4, 6-0.

Dolehide had herself a day in Palm Springs on the doubles court as well, as she and Alison Riske moved into the semifinals with a win over Sophie Chang and Alexandra Mueller, 6-1, 6-1.

The teenager's compatriot Taylor Townsend partnered Yanina Wickmayer to a 6-4, 6-7(5), 10-6 win over No.4 seeds Duan and Wang Yafan, while No.2 seeds Barbora Krejcikova and Vera Lapko saw off Andrea Petkovic and Francesca Schiavone, 6-3, 6-4.