The 18-year-old was by far the men's game's biggest riser, from No. 551 to Next Gen champ. (Getty)

The new year is almost upon us, and there's a crop of young players ready to make even bigger marks on the world in 2020. Let's count down the Top 10 ATP and WTA youth to watch: 

1

Jannik Sinner

Age: 18 

Ranking: No. 78

Jannik Sinner ended his 2019 the way he began it: unglamorously. His season-long whirlwind started with three consecutive ITF tournaments in Monastir, Tunisia, and finished at an ATP Challenger at home in Italy. 

The difference: that last event marked Sinners sixth tournament win of the year. Titles at three Challengers, two ITFs and the Next Gen ATP Finals took him from relative obscurity to touted future hope, and his ranking rose 473 spots, to No. 78, readying him for the main tour.  

Despite playing primarily in the lower tiers in 2019, he saw success in numerous big events, winning a Masters match, qualifying for the US Open and reaching the Antwerp semifinals—in addition to his straight-sets defeat of Alex de Minaur to become Next Gen champion.   

And perhaps the moment he officially became a factor on tour was when he starred in his first viral clip: 

In seriousness, he was truly recognized in December, when the ATP players voted him Newcomer of the Year. Still, as he starts 2020 in the top 100 instead of the No. 551, he'll likely feel like a newcomer all over again.