Four players were disqualified from the first round of the French Open on Thursday for a rule violation after hitting into the water on the last hole.
Rikard Karlberg of Sweden, Damien McGrane of Ireland, James Ruebotham of England and Jaco Van Zyl of South Africa all dropped their balls from the wrong place. Only if the ball went beyond a certain point were players allowed to use the drop zone.
''The local rules are very clear,'' European Tour senior referee Andy McFee said. ''It says at the 18th hole, the drop zone can only be used if the last point of entry is beyond the green stake.
''Players have to read and understand the local rules. Players spend hours and hours on the practice round trying to save a shot. Well, five minutes in the rule book can have exactly the same effect.''
Meanwhile, England's Graeme Storm shot a bogey-free 6-under 65 to share the lead with Australia's Richard Green.
They were followed by George Coetzee of South Africa, James Morrison of England and Thorbjorn Olesen of Denmark, all shooting 66.
Green had seven birdies to lead by two strokes in the European Tour event. But Storm picked up a shot on the 17th to bridge the gap with Green after the Australian bogeyed the same hole.
''It's nice to see my name on the leaderboard, especially coming out on 18,'' said Storm, who won the French Open in 2007. ''You kind of remember that you've won it before and you've been in this position before.''
Italian teenager Matteo Manassero shot a 68 to share sixth place with 10 other, after recovering from a double bogey on the second hole by making an eagle on the next.
Defending champion Miguel Angel Jimenez and Martin Kaymer were in contention at 71.
American Bubba Watson (74), 2008 winner Pablo Larrazabal of Spain (74), and last year's runner-up Francesco Molinari of Italy (75) will need lower scores on Friday to make the cut.
