Semifinal Saturday at the NextGen ATP Finals in Jeddah, Saudia Arabia begins with an all-American clash between Alex Michelsen and Learner Tien. Joao Fonseca and Luca Van Assche are also taking the court.

(2) Alex Michelsen vs. (5) Learner Tien

Michelsen and Tien will be going head-to-head for the first time in their careers when they meet in the semifinals of the NextGen ATP Finals on Saturday evening. Both Americans have been outstanding in 2024, with Michelsen really making a name for himself on the main tour. The 20-year-old American compiled a 31-29 match record at the ATP level this past season, surging to 41st in the rankings. His trek through the group stage in Jeddah was routine, beating Nishesh Basavareddy and Luca Van Assche in four sets before getting a retirement from Jerry Shang.

Tien has not yet made the leap to the big stage, but he was awesome at Challengers (four titles) and Futures (three titles) throughout the 2024 campaign. The 19-year-old American compiled a 2-1 round-robin record earlier this week, defeating Jakub Mensik in four sets, losing to Joao Fonseca in four, and upsetting Arthur Fils in four. Tien certainly has the talent to make this match competitive, at which point he could have an edge since he is more battle tested than Michelsen.

Pick: Tien in 5

(6) Luca Van Assche vs. (8) Joao Fonseca

Van Assche and Fonseca will also be squaring off for the first time in their careers on Saturday. Despite being the lowest seed this week, Fonseca has without question been the star of the show–which isn’t really a surprise since he is one of the top prospects in tennis. The 18-year-old Brazilian swept through his group with victories over Fils, Tien, and Mensik. Although main-tour success will mostly have to wait until 2025 and beyond, Fonseca did well to reach the quarterfinals at the ATP 500 in Rio de Janeiro in February.

Van Assche has already been around for a while on the pro circuit, slowly making his way to No. 63 in the rankings last fall before plunging outside the top 100 this season (currently 128th). The 20-year-old Frenchman went 8-17 at the ATP level in 2024 but has found his game in Jeddah, posting wins over Shang and Basavareddy to go along with a setback against Michelsen. Van Assche is an effective counter-puncher, but this match will be on Fonseca’s racket–which has been a good thing for the teenager so far this week.

Pick: Fonseca in 5