The joint leaders played early Thursday and are likely to find the course much tougher when they start their second rounds after lunch Friday.
The greens, softened by weeks of heavy rain, will become bumpy and unpredictable after being exposed to heavy player traffic.
That was the view of the world No. 8 Paul Casey after he shot a 68 late on the first day.
"I was maybe a little frustrated," he said. "I gave myself so many opportunities tee to green. I was pretty strong. But we had had a lot of traffic on the greens and a couple of putts slipped by.
"But the good news was that if I could play like that in the second round starting early when the greens will be fantastic, I will be able to take advantage of it."
Casey also remarked how different the conditions were in Munich, with damp fairways giving way to preferred lies, to those at Pebble Beach where he played last weekend in the U.S. Open.
"These greens are very receptive and you can throw the ball very close to the hole, where at Pebble Beach it was a question of playing the ball bump and run into the greens. I was not surprised that a couple of guys coming over from the States struggled."
The Spaniard didn't speak to reporters after his round. He has slumped from second in the world to 36th over the last 15 months, and is worried his run of five straight Ryder Cups is about to end.
"He isn't enjoying his golf at all at the moment," said Carlos Rodriguez, Garcia's manager. "It is not fun for him.
"Sergio has even said that if Colin Montgomerie were willing to offer him a Ryder Cup wild card he's not sure whether he would be of any help to the European team."