After seeing an early lead slip away, Anastasia Potapova rallied for a come-from-behind win against Coco Gauff on Saturday at the Miami Open. 

No.27 seed Potapova, who let a 5-2 lead slip away in the opening set, was one game from defeat trailing 7-6(8), 5-3 -- but won 10 of the next 12 games to claim a 6-7(8), 7-5, 6-2 win over the sixth-seeded American in 2 hours and 32 minutes. 

The win is Potapova's third career Top 10 win, and first since she beat then-No.2 Anett Kontaveit last summer in Prague. It was also her first win in three tries against Gauff.

Words from the winner: Potapova credited improved fitness for her ability to hang tough in hot and humid midday conditions at Hard Rock Stadium, and her mentality for being able to rise to the occasion when three points from defeat. 

"I think I just let it go, and I started to focus on my tennis and going for my shots and not thinking what she is going to do," Potapova said afterwards. "I'm really happy to be in the fourth round for the first time; it's a dream that really came true. 

"In those tough conditions, it's not easy to play ... Coco is an unbelievable athlete and she has very good fitness. I'm really surprised that I could stay at the same level until the end.. Thanks to my fitness coach!" 

Tale of the tape: Potapova opened the match strongly, finishing points and hitting through Gauff's defenses more often than not. She was also clutch in crucial moments, and saved the first seven break points she faced. But she failed to serve out the opener at 5-3, and the first set lasted more than an hour to set the tone for the match. 

The tiebreak was a back-and-forth affair that saw both players lead -- Gauff and 3-1, 5-3 and 6-5, and Potapova at 7-6 and 8-7 with serve -- before the American wrapped it up by winning the last three points. 

Turning point: Potapova had three game points for 4-4 in the second set, but was eventually broken on the first break point she faced in the set. Gauff was, in fact, three points away from victory serving at 15-0, but was instead broken to 15. 

Potapova later saved two break points in the 12th game before wrapping up the second set. 

Potapova only grew stronger in the decider, in which she won five straight games; in them, she lost just five points -- and three of those came at 2-2, where she broke Gauff at deuce.

Up next: Potapova will next play No.23 seed Zheng Qinwen of China in the Round of 16. Zheng extended her career-best showing in Miami by outlasting No.12 seed Liudmila Samsonova 5-7, 7-6(5), 6-3 in 3 hours and 7 minutes -- the 24th main-draw match this year to last more than three hours

Zheng takes down Samsonova for first time

Zheng battled back from 3-0 down in the third set, reeling off the last six games of the clash and getting back on level footing in their head-to-head at two victories apiece. Samsonova had defeated Zheng in their last two meetings, including last season’s Tokyo final.

In fact, before Miami, Zheng’s last scheduled match was against Samsonova in Dubai, but the Chinese player withdrew from that meeting with an abdominal injury. Her abdominal issues also forced her to skip Indian Wells.

But last season’s WTA Newcomer of the Year Zheng is back on track in Miami. On Saturday, Zheng slammed 18 aces en route to the gritty victory.

Zheng has beaten Potapova in each of their first two career meetings, including an epic in qualifying this year at the Adelaide International 2; Zheng was a 6-7(3), 7-5, 7-6(4) winner there in a staggering 3 hours and 36 minutes.