England's Daren Lee shrugged off a delay in the French Open to set the early pace moving to four under par after 12 holes.
Play began four hours late in the first round in Lyon today after heavy rain saturated the Villette d'Anthon fairways.
Due to waterlogging, the long par 5 fifth hole was reduced to a par-three, lowering the par figure for the course from 72 to 70.
The shortened course will play for the first round only, with the European Tour set to decide on the par figure for the second round after judging the condition of the fairways and greens.
David Higgins and Paddy Gribben are the only two Irish players currently on the course and are at level par and one over, respectively.
Ireland’s Paul McGinley, Philip Walton, Ronan Rafferty and Gary Murphy are all in the strong field but have yet to start their first rounds.