Karlsson (formerly Falck) turned a 0-1 deficit into a lead with two set wins, but Groth was able to level at 2-2 with 11-8 and force a tiebreaker.
There the Swede saved four match points to make it 10-10, but that was where it ended. Groth won two straight points and advanced to the second round.
He became a little more aggressive and I became passive. It changes quickly, Karlsson tells SVT.
Things went even better for Elias Ranefur. The Swede beat Romanian Iulian Chirita in three straight sets and will face 19-year-old Chinese player Wen Ruibo in the second round.
World number two Truls Möregårdh is the defending champion in the World Tour event and enters the tournament on Tuesday.
