Thiem's last ATP Tour win came against Hungary's Marton Fucsovics in May 2021Austria's Dominic Thiem spoke of his relief after winning his first match on the ATP Tour since May 2021.
The 2020 US Open champion, 28, spent nine months out with a wrist injury.
He lost his first seven matches after returning to action in March before beating Finland's Emil Ruusuvuori 3-6 6-1 7-6 (7-5) at the Bastad Open.
"It's a long time. My last victory was in Rome in 2021, it feels like a different world somehow," said Thiem, 28.
"Many, many things happened. It was tough, but it was also a very good experience I think, for life in general. I'm so happy that I got this first victory here today."
Thiem claimed his only grand slam title at Flushing Meadows in September 2020, coming from two sets down to beat Germany's Alexander Zverev in the final.
He has also twice made the final of the French Open, finishing runner-up to Rafael Nadal in 2018 and 2019, and was beaten by Novak Djokovic in the final of the 2020 Australian Open.
It has been a long road back for Thiem since retiring from a match against Adrian Mannarino in Mallorca 14 months ago. In that time he has fallen from fifth to 339th in the world rankings.
The Austrian chose not to play at Wimbledon, dropping down to the Challenger Tour, where he registered a win in Salzburg last week.
His next match in the second round at Bastad is against Spain's fourth seed Roberto Bautista Agut.
