The 39-year-old Stan Wawrinka beat Adrian Mannarino for the first time making history as the oldest man to win a match in Basel.
Brandon Nakashima remained perfect against Tommy Paul and reached the second round at the Erste Bank Open.
Thiem will be remembered for his ground-breaking tennis and his ability to deliver against the best.
"By coming here, you help the country," Rafael Nadal said responding to critics who called him a "sell out" for becoming Saudi Tennis ambassador.
The 36-year-old Roberto Bautista Agut beat Jiri Lehecka 7-5, 6-1 to win his 12th title in Antwerp and become the second-oldest ATP champion in 2024.
Tommy Paul becaem the fourth ATP player to earn three or more titles in 2024 with the win.
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