Henrik Bjornstad, Paul Eales, Marc Farry and a pair of 49-year-olds, Mark McNulty and Eduardo Romero, share third place after opening rounds of 5-under 66 at the Alpine Course at Golf Club Crans-sur-Sierre.
Karlsson opened on the back nine Thursday and bogeyed the 11th hole, but a run at the end of his first nine vaulted him up the leaderboard. He mixed four birdies and a bogey in his final five holes on the front side to make the turn at 2-under 33.
The Swede, who squandered a final-round lead last week at the BMW International Open, birdied No. 1 and eagled the short, par-4 seventh to post the early lead in the clubhouse.
'It's easy to relax here and have a good week with the family,' said Karlsson. 'I think people try to relax and enjoy the village. When the practice facilities are not so great people tend to practice less, enjoy it more and play even better. Every time I step onto the seventh tee the view puts a smile on my face.'
Karlsson, despite the mishap last week in Germany, can take several positives out of his round at the course Thursday. He went wire-to-wire last year for his fifth European Tour victory.
Els flew out of the gate Thursday with a pair of birdies at 1 and 2. He birdied three out of four holes from the seventh but fell off the pace with a bogey at No. 13.
Els, the current money leader, birdied 14 and 16 to match Karlsson atop the leaderboard.
'I am not complaining,' said Els, who fired a final-round 64 last week in Germany. 'I finally made some putts towards the end of last week's tournament so I felt good coming into this event. I think it's the first time I've gone deep into red figures on this course and I am looking forward to the rest of the week.'
Els benefited from a favorable pairing Thursday. His playing partners, Michael Campbell and Ricardo Gonzalez, each carded rounds of 4-under-par 67.
'It was a good three ball with Michael Campbell and Ricardo Gonzalez shooting 4 under par,' said Els, who won last year's British Open. 'It felt good to feed off the other guys.'
Campbell and Gonzalez were joined in a tie for eighth by Richard Bland, Sergio Garcia, Anders Hansen, Peter Hedblom, Maarten Lafeber, Miguel Angel Martin, Alessandro Tadini and Patrik Sjoland.
Sjoland fired his round of 67 thanks to a hole-in-one on the eighth. His 7-iron tee ball took two hops and disappeared below ground, earning the Swede an Omega watch.