STANFORD, CA, USA - No.3 seed Madison Keys survived a stern test from teenaged compatriot Caroline Dolehide to reach the quarterfinals at the Bank of the West Classic on Wednesday, ralling from a set down for a 3-6, 6-2, 6-3 victory.

"I think I finally just took a big deep breath, and restarted the match and settled in a lot more," Keys said on court. "It was definitely a lot faster out here today - she hits a really big ball - and it took me a little bit to kind of figure myself out. I'm feeling really good - I wasn't playing great and I turned it around. Things are starting to look up and I'm really happy about that."

Keys was pushed every step by her younger compatriot, who came into the tournament ranked World No.212 and a qualifier.

Dolehide took advantage of her oppotunities in the opening set, as she broke the Keys serve twice - despite the World No.21 landing 77% of her first serves - and dropped just two points on her own first serve in five games. 

The No.3 seed hit 11 unforced errors in nine games of the opening set as she struggled to find her range, while Dolehide played a more composed opener with five winners to seven unforced.

The 18-year-old served at 70% in the first set, and won all of the points behind her returns of Keys' second serve.

"I always think it's really hard when you're playing someone who's had three matches and it's your first match," Keys assessed post-match. "I just had to start making balls to find my rhythm, and once I did that, I feel like everything slowly clicked and I could start going for more of my shots. I was definitely going for way too much, way too soon...I regrouped, took a step back, and gave myself a little bit more time."

However, from a break down in the second set, Keys took charge, winning the next four games en route to tying the match at one set apiece, and making an early break stand up in the decider en route to victory in one hour and 36 minutes.

The No.3 seed ended the match with 26 winners to 23 unforced errors, broke serve three times in the second set and once in the decider, and never faced break point again after trailing 3-6, 0-1. 

"It was one of those matches where I figured it out in the middle of the set, and was able to settle in," Keys said. "It was more the kind of progession of not playing well, figuring it out, being conservative and then going for it - I'm really happy with how I did that today."

The win for Keys sets up a quarterfinal meeting with No.7 seed Lesia Tsurenko, who advanced without hitting a ball on Wednesday as Maria Sharapova withdrew due to injury.

The other day session singles match saw No.5 seed Ana Konjuh edge Natalia Vikhlyantseva, 6-4, 7-5 to advance to the last eight, where she'll face the winner of Wednesday night's match between top seed Garbiñe Muguruza and American teenager Kayla Day.