England's Barry Lane battled a knee injury on the way to a 6-under-par 66 in the first round to share the lead with five others, including Marc Cayeux of Zimbabwe, who filled in for injured Italian Emanuele Canonica.
Also carding 66s at Golf Club Gut Larchenhof were Austria's Markus Brier, Welshman Bradley Dredge, England's Andrew Marshall and Peter Senior of Australia.
The leaders stand one stroke ahead of a group of seven players tied for seventh place at minus-5, including world No. 5 Retief Goosen and four-time champion Bernhard Langer of Germany.
All in all, there are 65 players within five strokes of the leaders.
Lane aggravated a knee injury while practicing on Tuesday, but that didn't stop the 45-year-old from carding a bogey-free round. He played 3 under on both sides and hit one of the day's best shots at the par-3 eighth, where his tee shot landed within an inch of the hole.
'When I woke up this morning I said to my wife, 'I really don't know if I will be playing today,'' acknowledged Lane, the 1992 champion. 'It was that bad. But I took some anti-inflammatories and...I played. Hopefully it is going to be all right for tomorrow, but you never know.'
Cayeux collected seven birdies in his first round after Canonica withdrew because of a neck injury. The 27-year-old's only dropped shot came with a bogey at the 582-yard par-5 seventh.
'Being here Monday, Tuesday and Wednesday and not knowing if you are playing or not is a horrible thing,' said Cayeux. 'There is always one guy every week who is the first alternate and it's not a nice position to be in, but this week it was me.'
In fact, Cayeux, who has played in 25 European Tour events this year, wasn't sure he was even going to stick around as the first alternate.
'To be honest, the way I felt, I wanted to go home,' admitted Cayeux. 'This morning I even looked on the Internet to check my ticket and change it to go back home to Zimbabwe. I have been five months away and haven't been home and I am really tired. But I'm glad I didn't now.'
Senior and Dredge matched Lane with bogey-free rounds of their own, while Brier stumbled to a pair of bogeys and Marshall dropped just one shot. Brier's round included a 45-foot eagle putt at the par-5 third -- his 12th hole.
Langer carded eight birdies in his round, but also stumbled to three bogeys on the day. After consecutive bogeys at Nos. 9 and 10, he rattled off birdies in four of his next five holes to reach minus-5.
'I made two stupid bogeys...and that really got me upset in a way,' said Langer, who is a co-promoter of the event with his brother. 'I went back to one under, and then got three (birdies) in a row after that and played solid the rest of the way.'
Defending champion Padraig Harrington of Ireland sputtered to a 3-over 75 and is tied for 116th place with seven others. He is one of just 45 players who finished their rounds over-par. Eighty-seven others were even-par or better.