Things did not look good for Madison Keys when she was down a set and a break in her fourth-round match at Wimbledon with 16-year-old Russian Mirra Andreeva on Monday.

But spurred by an on-court pep talk from her fiancé, ATP player Bjorn Fratangelo, Keys, a natural power-hitter from the baseline, changed tactics and began to attack by coming to the net more often.

“I got a pretty good pep talk from Bjorn in the corner, reminding me it’s just a break, it’s one break, it feels bigger, but keep trying to put pressure on her and I did,” Keys told Mary Joe Fernandez on ESPN.

“I kind of can’t believe that I came out with the win,” the 28-year-old Keys added following her 3-6, 7-6(4), 6-2 win.

Keys has now won nine straight grass court matches after taking the Eastbourne title coming into Wimbledon. She is into her second Wimbledon quarterfinal (2015) and will face the winner between No. 2 Aryna Sabalenka and No. 21 Ekaterina Alexandrova.

Keys is one of two American women into the quarterfinals along with No. 4 Jessica Pegula, the top-ranked American woman and the daughter of Buffalo Bills owners Terry and Kim Pegula. Pegula meets Markéta Vondroušová of the Czech Republic on Tuesday.

Quarterfinalists will take home $430,347, while semifinalists earn $759,436. The champion will take home $2,974,458.

“I’ve really been just trying to keep it simple,” Keys said of her grass court success. “I think sometimes I feel like I have too many options and kind of last-minute decisions, and they’re not always the smartest, so really just trying to keep it a lot more simple and just play the smart shots over and over and over again and if I’m able to do that pretty consistently, a lot of times I’m able to get the win.”

Keys won 25 of 43 net points against Andreeva, a rising star in the women’s game, and saved 8-of-12 break points.

“She’s a really great player and I knew obviously, being 16 and a qualifier, she was going to go out and play some of her best tennis,” Keys said. “She serves really well, she does a really good job of moving out of the corners, which definitely makes it tough. But I was the veteran on the court today.”

Keys is back in the quarters at Wimbledon for the first time in eight years and will face a big-hitter regardless of who wins the Sabalenka match.

“Honestly, I like it,” Keys said. “I’ve always really enjoyed those hard-hitting matches and I feel like sometimes they go your way and sometimes they don’t. But honestly, either way it’s going to be a really tough match and I’m really looking forward to it.”