On a tough day for seeded players in the Swiss Indoors first round, Stan Wawrinka rallied to beat 119th-ranked fellow Swiss Marco Chiudinelli 6-7 (1), 6-1, 6-4 on Tuesday.
Top-seeded Wawrinka advanced after second-seeded Milos Raonic and sixth-seeded Grigor Dimitrov both let one-set leads slip and exited early.
Wawrinka ended his own streak of four straight first-round losses in the hometown tournament of Roger Federer, whose season-ending injury ruled him out for the first time since 2005.
World No. 3 Wawrinka clinched victory with his 16th ace on his fifth match point chance against his Davis Cup teammate Chiudinelli. He next plays qualifier Donald Young of the United States.
The bottom half of the draw opened up Tuesday after Canada's Raonic lost to Ricardas Berankis of Lithuania, a player ranked 87 places below him.
The fourth-ranked Raonic took the first set against his 91st-ranked opponent before falling to a 3-6, 6-3, 6-3 loss.
The 26-year-old Berankis now has two career wins against top 10 players, after also beating Raonic indoors in Moscow two years ago.
Dimitrov of Bulgaria let 37th-ranked Gilles Muller of Luxembourg fight back for a 6-7 (9), 6-4, 6-4 win after taking only one of his 10 break point chances against the 33-year-old left-hander.