Joao Fonseca has been studying the David Goggins mentality: “I’ve been learning a lot!” 

Joao Fonseca is working on his mental toughness — and learning to embrace the grind, David Goggins-style.

The world No. 49 made a winning Cincinnati Open debut on Thursday, rallying past Yunchaokete Bu 4-6, 6-2, 7-5 in a hard-fought first-round battle. (Watch the replay on Tennis Channel.)

The match was played on the newly revamped P&G Stadium—part of a sweeping renovation that has doubled the size of the Lindner Family Tennis Center and added modern facilities and courts. For Fonseca, the transformation is all new.

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“For me, it’s (all) new,” he told Steve Weissman at the Tennis Channel desk. “People say here has changed a lot, and I mean, it’s just super cool. Everything is just super modern and it’s just super nice for me. This has been my favorite Masters 1000 (so far).”

One thing did feel familiar:

“The heat is like Brazil!” Fonseca joked. “But at the same time, I feel like I’m a little bit at home—a lot of Brazilians in the crowd, and it’s just super nice.”

Known for his power hitting, Fonseca had to mix things up against Bu, coming forward to the net, changing direction smartly and showing patience in constructing points.

“A tough match today against a very great opponent,” he said. “The first half was really tight, I was a little bit more nervous than usual, but it’s normal in the first round.

“Yeah, I started out struggling a little bit, but after playing much better I got the win. I’m very happy with the way that I played today.”

So how did he push through the heat, nerves and a slow start? Fonseca revealed our Tennis.com Quote of the Day inspiration: he’s been reading David Goggins.

Q. Every tournament is kind of a new experience for you as you’ve been rising up the ranks. What are some things that you’ve been learning about yourself throughout this year?

FONSECA: I mean, I’ve been (away) from my family a lot, so I’ve just been staying with my team. I’ve been working, learning a lot with them.

I mean, I’ve learned to read more! I wasn’t the type of reading guy, so now I’m reading more books.

I’m now learning from David Goggins, it’s good. I’ve been learning a lot of things!

Goggins—a New York Times bestselling author, US Armed Forces veteran, ultra-endurance athlete and motivational speaker—is known worldwide for his extreme mental and physical toughness. His biggest lesson for Fonseca?

“Nothing that you’ve (never) heard before, like stay positive, stay fighting,” Fonseca explained. “Like, keep pushing when things get hard, how to stay pushing—yeah, those kinds of mentalities.”

Fonseca will look to channel that mindset in the second round against No. 17 seed Alejandro Davidovich Fokina. A win would mark his first Top 20 victory since the Miami Open in March, when he defeated No. 19 Ugo Humbert on his way to the third round.

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Last week in Toronto, Fonseca fell in two tight sets to Tristan Schoolkate—but as Goggins says: "The only limits you have are the limits you believe."