Bulgarian Grigor Dimitrov rallied after dropping the first set to Elias Ymer, a Swedish wild card ranked 1,032nd, to secure a 5-7, 6-2, 6-4 victory in the opening round of the SkiStar Swedish Open.
The fifth-seeded Dimitrov was broken twice in the opening set before finding his service form and taking control of the nearly two-hour match.
The 17-year-old Ymer was playing in his first ATP Tour-level match.
In other matches, Argentine Carlos Berlocq upset seventh-seeded countryman Horacio Zeballos 6-4, 6-3 and Argentine Martin Alund overcame another Swedish wild card, Markus Eriksson, 7-5, 6-7 (5), 7-6 (8) in a 3-hour, 25-minute battle.
Top seed Tomas Berdych of the Czech Republic has a bye in the first round.