After a wrist injury past year cost Rafael Nadal his streak of 11 consecutive top-five seasons, the King of Clay came back stronger than just about anyone could have anticipated, a journey that he cemented on Wednesday by clinching his finish at World No. 1.
"One year ago for sure I never dreamed of being world No 1 at the end of the season so I'm very happy for everything".
His absence paved the way for Rafael Nadal, who secured his place at the top of the ATP rankings with victory over Hyeon Chung.
Roger Federer has pushed Nadal all the way in the battle to finish atop the rankings, with both players enjoying remarkable comebacks in 2017.
"It means a lot".
'I'm happy to achieve the year-end world No. 1 here in Paris'.
It marks the conclusion of what has been a remarkable season of renaissance for Nadal, who overcame wrist problems from previous year to win the French Open and US Open - his 15th and 16th grand slam titles. It has been an unbelievable year.
The 16-time Grand Slam champion completed his rise back to world number one for the first time in over three years in August.
The South Korean world No 55 has enjoyed a breakthrough season in 2017 and will play at the inaugural Next-Gen Finals in Milan later this month and although he levelled for 5-5 he paid the price for his efforts as Nadal sealed the set with two successive games.
Having sat out last week's event in Basel to rest his knees after a successful hard-court season, he put in a patchy performance.
He will next face Uruguayan Pablo Cuevas, who ended a 10-match losing streak in round one and backed that up with a 6-7 (5), 7-6 (1), 6-2 victory over the 15th seed Albert Ramos-Viñolas.
The defeat dents Carreno Busta's chances of qualifying for the season-ending ATP Finals in London - he is dependent on other results here - while Querrey's bid to reach London is over.
Also, fourth-seeded Alexander Zverev lost to Robin Haase 3-6 6-2 6-2, and ninth seed John Isner beat Diego Schwartzman 7-6 (7-2) 6-7 (13-11) 6-3.