PARIS -- Coco Gauff sat plain-faced in her French Open changeover chair after moving one set away from her first Grand Slam final at 18 -- just 18! -- and calmly snacked on some cut-up pieces of pineapple and other fruit, seemingly without a care in the world.
Her opponent in Thursday's semifinals at Roland Garros, Martina Trevisan, was taking a medical timeout so her right thigh could be treated and taped by a trainer. It was the sort of delay that might rattle some players, might make them cool off, relinquish momentum, think too much about what was at stake.
Not Gauff. Not on this sunny, breezy afternoon at Court Philippe Chatrier. When the American arrived in Paris, she celebrated her recent high school graduation by posing for cap-and-gown photos near the Eiffel Tower while holding her diploma. After wrapping up a 6-3, 6-1 victory over the 59th-ranked Trevisan, Gauff will be back in that stadium Saturday to face No. 1 Iga Swiatek for the championship.
"I'm in a mindset now like: 'It doesn't matter.' I mean, I'm going to be happy, regardless. My parents are going to love me, regardless. So I'm just going to go into it like another match,'' the 18th-seeded Gauff said. "I mean, yeah, it's a Grand Slam final, but there are so many things going on in the world right now, and especially in the U.S., a lot of stuff is happening right now, so I think it's not important to stress over a tennis match.''
And then, in a message referring to the recent series of mass shootings in her home country, Gauff wrote in marker on a courtside TV camera: "Peace. End gun violence.''
"I think that this is a problem, you know, in other parts of the world, but especially in America it's a problem that's, frankly, been happening over some years but obviously now it's getting more attention. But for me it's been an issue for years," Gauff said of the message.
"For me, it's kind of close to home. I had some friends that were a part of the Parkland shooting back in -- I don't remember which year. I remember watching that whole experience like pretty much first-hand, seeing and having friends go through that whole experience. Luckily they were able to make it out of it. I just think it's crazy, I think I was maybe 14 or 13 when that happened, and still nothing has changed."
Gauff said she didn't plan to write that but "it just felt right in that moment," especially considering that she woke up to the news of a shooting at a Tulsa, Oklahoma, hospital that left four dead. She also said her family and team encourages her to use her voice and that she has been inspired by other athletes doing the same.
A willingness to speak out about issues of significance -- and a wide-lens view of the world -- reflects the sort of maturity that has served her well, especially with so much attention from such a young age. She won the French Open junior title at 14. She became the youngest qualifier in Wimbledon history and then beat Venus Williams on the way to the fourth round there at 15.
Gauff, who turned 18 in March, is the youngest woman to reach a Grand Slam final since 17-year-old Maria Sharapova at 2004 Wimbledon and the youngest American woman to reach a major final since a 17-year-old Serena Williams at the 1999 US Open.
She's also the youngest finalist at the clay-court major tournament since 2001, when Kim Clijsters was the runner-up a day after her 18th birthday.
"I'm a little bit in shock right now,'' Gauff said with a chuckle after using her still-improving forehand to open up the court and her long-terrific backhand to seal points against Trevisan. "I didn't know how to react at the end of the match. I have no words to describe how I feel.''
Gauff has won all 12 sets she has played over the past two weeks. She did not need to navigate the most arduous path to get this far: Because of all manner of surprising results and early exits by top players from the bracket, she has faced only one seeded foe so far, No. 31 Elise Mertens.
Trevisan, 28, is a left-hander who entered the day on a 10-match winning streak, including her first career WTA title at Rabat, Morocco, a week before play began at Roland Garros. She also defeated Gauff the only previous time they played -- in the second round in Paris two years ago.
But Gauff is nothing if not a learner and a striver, someone who looks better and better with a racket in her hand each time she takes the court. A big part of that, perhaps bigger than her speedy serves that reached 115 mph (185 kph) on Thursday, is her preternatural cool, an old soul's ability to see an obstacle and not be daunted.
Early on, a Trevisan shot landed near a baseline and was ruled in to make it 30-all. Gauff asked chair umpire Marijana Veljovic to come get a closer look, and the pair engaged in an extended discussion, both pointing at the landing spot. Gauff crouched down to inspect as some spectators whistled and jeered, as they often do here when players argue a ruling.
A smattering of boos then cascaded on Gauff when she walked to the net to check a mark after one of her backhands landed wide during a game in which Trevisan would break back to make it 3-all.
Unbothered, Gauff broke right back to lead 4-3, smacking a backhand winner that brought Mom and Dad out of their seats in the player guest box. The match would continue for about 50 more minutes, but the outcome would never again be in any real doubt.
"Honestly, I wasn't nervous going in today. I haven't been nervous at all, which is a surprise,'' Gauff said. "The only time I get a little nervous is maybe in the morning. I go for a walk in the morning so that kind of clears my head, and after that, I feel great.''
The Associated Press and ESPN's D'Arcy Maine contributed to this story.