The three-time grand slam winner was beaten 7-5 7-6 (7-2) on Tuesday (Wednesday AEDT) by eighth-seeded Czech Jiri Lehecka in the first round of the Swiss Indoors.
Wawrinka's last shot as a professional tennis player was a backhand that landed wide — to the audible disappointment of the vociferous home crowd.
"It's not up to me. There are different visions of me as a player over the past 20 years," he told ATPTour.com when asked about his legacy.
"For me, all I wanted in my career was to give everything, to have no regrets, to always fight, to always give 100 per cent in every match — out of respect for myself, for the opponent, for the tournament, for the fans, for everybody.
"That's ... the only way you can leave the sport: without any regrets."
Wawrinka, who turned pro in 2002, announced last December that 2026 would be his last year on tour and "Stan the Man" had received warm send-offs throughout his farewell season.
The 41-year-old earned his three slam titles after defeating the then-World No.1 player in each final. He beat Rafael Nadal to win the 2014 Australian Open and downed Novak Djokovic for both the French Open title in 2015 and the US Open the following year.
Wawrinka, who reached a career-high world No.3 ranking in 2014, won 16 tour-level titles.
He also paired up with Roger Federer to win doubles gold at the 2008 Beijing Olympics and the duo helped Switzerland claim their first Davis Cup title in 2014.
Earlier in the day, top seed Ben Shelton fired down 44 aces to weather a first-round scare from lucky loser Aleksandar Kovacevic.
The world No.4, who reached the Basel final in 2024, won the two-hour 36-minute opener 6-7 (4-7) 7-6 (7-3) 7-6 (7-4) against his fellow American to set up a clash with Swiss wildcard Jerome Kym, a 7-6 (7-1) 6-4 winner over Frenchman Arthur Rinderknech.
"I'm pretty excited about that," Shelton said when he was told how many aces he hit.
"We changed my serve, the technique. To come out here in the first match and serve the way that I did, I'm very pleased with that. This is how you win on fast indoor courts."
Spanish sensation Rafael Jodar, currently ninth in the Race to Turin, and Arthur Fils of France, who's currently seventh, also recorded straight-sets wins, while the US's Alex Michelsen won in three.
At the other ATP 500 event in Vienna, Germany's top seed Alexander Zverev saved four match points in the third-set tiebreaker to defeat Martin Landaluce of Spain 7-5 3-6 7-6 (13-11).
Other winners in round one included second seed Carlos Alcaraz, fourth-seeded Italian Flavio Cobolli and Brit Cameron Norrie.
With AAP.
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