The American shot a six-under-par 66, while both Australians recovered from mid-round bogeys to finish on 68 at the Green Eagles Golf Courses in Hamburg on Thursday.

Dodt birdied seven times, while Hend birdied five times in the first round.

Three Frenchmen, Joel Stalter, Romain Wattel and Mike Lorenzo-Vera, and Germany's Benedict Staben, are just a shot behind DeChambeau.

"It's great to start out with six-under par. I think it's one of my lowest rounds on the European Tour so I'm very pleased," the World No.23, playing in only his sixth regular tournament on the European Tour outside of the majors and WGC events, told europeantour.com.

"I haven't been hitting it my best so I'm still working on my game and it's starting to turn into some form.

"I'm missing in the right places and making some putts which is great. If you do that out here you're going to be up there."

DeChambeau holds a one-stroke lead after the opening round of the European Open. PHOTO: Matthew Lewis/Getty Images.

Starting at the 10th he carded four birdies in his opening nine holes and – although he dropped a shot at the par-4 3rd – he produced three further birdies in his last six holes, including a brilliant approach to the 517-yard last with his third from behind a tree.

DeChambeau comfortably outscored tournament favourites, Paul Casey and Patrick Reed.

World No.15 Casey briefly had a share of the lead at four under through nine holes, including an eagle on the par-5 18th, and a birdie at the last saw him bounce back from a double bogey at the short 8th.

That left him in a large group, including compatriot David Horsey and Scotland's David Drysdale, on three under.

Among those a shot better off were Welshman Bradley Dredge, and English pair Steven Brown and Oliver Fisher.

Reed, who appeared to be hampered by a knee injury, fought to make pars on many holes and closed on two under.

Australians Harrison Endycott and Matthew Perry are just five shots off the lead on the congested leaderboard.