Green and Storm head field

Left-hander Green, twice a runner-up in the event, set the pace with seven birdies and just one dropped shot. Storm caught him with a blemish-free card containing six birdies.

The pair head last week's Munich runner-up George Coetzee of South Africa, Thorbjorn Olesen of Denmark and Briton James Morrison.

Green's latest bid to claim the French title was inspired by having his family in the gallery, he told reporters. "My parents are watching me for the first time in a long time and my daughter is walking around with me which is great."

Englishman Storm has had a moderate season so far, missing six cuts, but said he is always lifted by playing this event - even though it creates certain difficulties for him.

"People keep saying to me when you go to the French Open you always play well and it was a little bit of added pressure," he said. "So I committed to every shot and it turned out great."

American Bubba Watson, on a large appearance fee, had a disappointing start to his first regular European Tour event and said he may just stick to his home tour from now on - even though he is down to play next month's Scandinavian Masters the week after appearing in the British Open.

After double-bogeying the last for a 74, the powerful left-hander, runner-up in last year's U.S. PGA Championship said after being asked if he would be playing more on the European Tour: "I think this might be the only one. I miss my home."

Tournament favourite and former French Open winner Martin Kaymer, the player who beat Watson for the 2010 U.S. PGA title, carded a 71 to trail the lead by six strokes.