Gauff outlasts Bencic to reach Miami semi-finals

But the 22-year-old from Florida, who lives in nearby Delray Beach, was determined to play in what she considers to be her hometown tournament where she had never previously gone further than the last 16.

Gauff's sense of determination was on full display at the Hard Rock Stadium's main court on Tuesday as she weathered fluctuating form against the 12th-seeded Bencic to grind out victory.

"I honestly didn't think I would be in the semis so I'm really happy and proud of myself," Gauff said. 

"I think I proved a lot to myself this week, and I feel like with each match I'm getting better.

"Even though I'm still playing three sets, I feel like the level is getting better and better."

Gauff, the French Open champion, will now face the Czech 13th seed Karolina Muchova in the last four as she chases her first Miami final appearance. 

Gauff has won all five of her previous matches against Muchova.

"You don't think about the head-to-head," Gauff said. 

"There's so many matches that we play that could go either way. I don't really think about it -- especially when I play here, because I know how good she is."

Muchova advanced to the last four earlier with a 7-5, 7-6 (7/5) defeat of Canadian 10th seed Victoria Mboko.

The 29-year-old Muchova admitted she had everything to prove against Gauff.

"I don't have the best record against Coco, but I feel good," Muchova said. "And you never know."

Despite giving away 10 years to the teenaged Mboko, Muchova said she did not feel any sense of disadvantage against her younger opponent.

"I keep getting these questions this week like I'm really old or something," Muchova said. 

"I don't feel that old -- I feel like I'm still pretty young. In my head, I could be 20."

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