There are currently 15 ATP Young Guns, with two new additions being added this week — American Bjorn Fratangelo and Russian Karen Khachanov.

22-year-old Fratangelo joins the Young Guns family ranked at No. 99, moving four places up from last week to break into the Top 100 for the first time in his career.

Khachanov moved up 10 spots to a career-high ranking of No. 98. The 20-year-old has already had a major Top 20 win in his career, as he defeated then-No. 17 Roberto Bautista Agut in Barcelona.

With Fratangelo and Khachanov joining the Top 100, that leaves 25 aspiring players aged 23 and under ranked within the Top 200. Let’s take a look at who has the most potential for breaking into the Top 100 in the second half of the season.

Frances Tiafoe 

American Tiafoe has already made headlines before, as his dramatic rise through the rankings garnered a lot of attention. The 18-year-old started January 2015 ranked 1142 and within 10 months he broke into the Top 200. He also earned a wildcard into The French Open and the U.S. Open, unfortunately falling in the first round both times. Perhaps the quickest ascent in the rankings in years, Tiafoe has shown the potential to be a mainstay in the Top 100… Even Brad Gilbert thinks so.

Tiafoe, currently ranked No. 175,  has already beaten several Top 100 players and pushed others to the brink. The 6-foot-2 teenager breezed past Sam Groth 6-3, 6-3 at a Challenger in Texas.

He followed that up by overcoming current Young Gun Taylor Fritz (then ranked No. 80) at his first career Masters 1000 tournament in Indian Wells. After defeating Fritz at their first ATP tour level match, he nearly overcame then-No. 18 David Goffin, narrowly losing in a third-set tiebreak. Tiafoe also defeated then-No. 81 Donald Young at a Tallahassee Challenger where he made it to the finals, before following to fellow teenager Quentin Halys.

Tiafoe’s quick success on the tour is due to his size (he’s a strong 6-foot-2) and his speed and explosiveness. His aggressive movement translates into his quick-strike style of play, where he looks to dominate points early and close points out at the net. Once Tiafoe adds more variety into his game, he’ll be able to regularly compete with the more consistent players within the Top 100.

Quentin Halys

Frenchman Halys moved up 10 spots in the rankings to hit a career-high No. 144 on Monday. The 19-year-old is familiar with Tiafoe, as they’ve played twice at Challengers since turning pro with Halys taking both of the matches.

Since turning pro in 2014, Halys has posted some solid results. He’s won four titles so far, three of them being Futures and his first Challenger in Tallahassee.

Halys started 2016 with a wildcard to the Australian Open. He didn’t squander the opportunity to play in the main draw of a Grand Slam, as he overcome No. 78 Ivan Dodig in four sets. Halys was ranked No. 187 at the time of his first career Grand Slam win, but unfortunately had to face eventual-champion Novak Djokovic in the next round.

After receiving a wildcard at the French Open for the second consecutive year, Halys won his first round match over former Young Gun Hyeon Chung. Unfortunately the Frenchman lost his second round match to No. 27 Pablo Cuevas, but did push him to two tiebreak sets.

Like Tiafoe, the Frenchman is quite tall with a frame of 6-foot-3. Halys’ strengths are his serve, his aggressive, flat forehand and his ability to charge the net and close out points. Not a lot of players are comfortable at the net, or will willingly come in to finish off the point, but Halys’ success in doubles gives his game more variety than most (he’s currently ranked No. 378 and won the 2014 French Open boys’ doubles title).

While Tiafoe is already on Gilbet’s radar, I expect Halys to find success within the Top 100 as well. Who do you think is more likely to break into the Top 100 first, Tiafoe or Halys?