A virtual unknown on the Tour at the start of the season, the former top-ranked junior lit up Wimbledon and the US Open with mesmerizing performances, capturing the world's attention and turning her into a superstar overnight, with a string of lucrative endorsements.
On Sunday, Gauff overcame former French Open winner Jelena Ostapenko of Latvia in three sets to win the title in Linz, Austria, making her the youngest WTA champion since Czech Nicole Vaidisova won in Tashkent 15 years ago.
'It's been crazy,' Gauff told CNN Sport in a phone interview from Linz.
READ: How Coco Gauff become tennis's youngest champion in 15 years
Venus and Serena
Venus and Serena Williams, Gauff's idols, were both 17 when they won their first WTA titles.
Gauff finished 2018 ranked just inside the world's top 700, but she soared into the top 100 at No. 71 Monday, guaranteeing her direct entry into the four grand slam tennis events, starting with the Australian Open in January.
'Definitely (at) the beginning of the year my goal was to be top 100, and get to the main draw of one slam,' said Gauff, who was given a bottle of red wine, a traditional Austrian Dirndl costume and a cheque for $43,000 for winning her first big title.
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Wimbledon, US Open
Gauff, who won the junior Roland-Garros title in 2018 at the age of 14, was given a wild card into the qualifying event at Wimbledon in June, and grasped the opportunity with both hands, becoming the youngest player in the Open era to reach the main draw.
It was then that her sensational summer began.
First she ousted former champion Venus Williams in the first round and reached the last 16, where it took the eventual winner Simona Halep of Romania to stop her.
Her Wimbledon exploits earned her a wild card into the main draw at the US Open, where she reached the third round before losing to 2018 champion Naomi Osaka of Japan.
'I've pretty much accomplished all my goals for this year and now I'm just playing to continue to better them,' said Gauff, whose performances at Wimbledon had drawn praise from the likes of Michelle Obama.
'I haven't really thought about next year, just because this year, I guess that everything that's accomplished for this year was probably on the timeline for two years from now,' added the American, who made the cover of Teen Vogue in the runup to the US Open.
Gauff's win in Linz, a city located on the Danube in Upper Austria, was all the more remarkable because she had started the week with a 6-4 6-2 loss in the final round of qualifying to Tamara Korpatsch, a German ranked 124th in the world.
But when Maria Sakkari of Greece withdrew through injury, she received a lucky-loser place into the main draw.
'Starting the tournament I felt I wasn't that confident in my game but after today, I feel like after each match went by, I got more and more confident,' said Gauff, who knocked out world No.8 Kiki Bertens of the Netherlands in the quarterfinals.
Because she is only 15, Gauff is restricted in the number of events she can play under the WTA's Age Eligibility Rule (AER), which was introduced two decades ago to protect young players from early-career burnout.
Under the rules, Gauff can play a maximum of 14 events. As Linz was her 10th tournament, that means she has four events left to play until she turns 16 in March and will be free to enter as many events as she wants when she turns 18.
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The best is yet to come
The more she'll play, the better she'll get, says Gauff, who will finish her year by playing in this week's WTA event in Luxembourg.
'It's always going to be a continuing process, just because I'm all new to the Tour, I haven't played that many players so my confidence may not be that high, but I think the more matches I play, the more confidence I'll (gain), just because the more experience I'll have,' she said.
Although Gauff played a smart match against the hyper-aggressive Ostapenko, absorbing the power and mixing up the pace, it looked for a moment as if the wheels were coming off at the end of the final set, when the Latvian saved two match points with huge hitting as she trailed 5-0.
After Ostapenko held, Gauff played a passive service game and was broken to love. It took a chat with her father and coach, Corey Gauff, during the changeover to help steady her nerves.
'You are not going to sprint to the finish line, you are going to walk to the finish line,' said Corey Gauff, who had flown in from Florida with his wife and Gauff's mother, Candi, the day before.
'He was trying to calm me down because he knew I was nervous and I was close to the finish line and I needed to close out,' said Gauff. 'He was telling me to kind of swing for my shots, and go for my shots.'
She did just that in the next game, taking the title on her third match point, thanks to a successful Hawk-Eye challenge, before putting her hands on her head in disbelief.
'You have a bright future, and I am really glad to share the court with you,' Ostapenko told Gauff at the trophy ceremony.
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'It's been an unbelievable week and definitely one of the biggest accomplishments of my career so far,' said Gauff.