Meath golfer Damien McGrane is one of four players to be disqualified on the first day of the French Open.
He was eliminated after he took a wrong drop on the 18th hole.
They were disqualified after a "serious breach of the water hazard rules on hole 18, taking a drop from the wrong place", the European Tour said in a statement.
McGrane was the highest profile casualty of the four.
He was joined by South African Jaco Van Zyl, Rikard Karlberg of Sweden and Britain's James Ruebotham were also disqualified.
All sent balls into the lake at the 18th and then played from the wrong spot after taking penalties.
The Players had been instructed of the right way to drop the ball prior to pay.
"One player said he had read the notice explaining how to drop the ball correctly but forgot it and the other three said they had not read the notice," European Tour chief referee Andy McFee told reporters.