Saint-Quentin-en-Yvelines - Rory McIlroy had a stop-start opening to the 100th French Open at Golf National on Thursday, as Dane Lucas Bjerregaard fired a hole-in-one and opened up a one-shot clubhouse lead.
World number four McIlroy managed four birdies against four bogeys in an even par round of 72 to sit five adrift of the early lead.
Starting on the 10th, consecutive birdies at 14 and 15 got the four-time major champion off to a quick start, but he handed them back on the front nine.
Despite not being a spectacular opening to his first visit here since 2010, it was a good return for McIlroy after missing the US Open cut at Oakmont.
The Northern Irishman opted to play in this tournament over the WGC Bridgestone Invitational because of the double Ryder Cup points on offer, but he was overshadowed on the first morning by two youngsters.
The 24-year-old Bjerregaard's magical moment came on the par-three second hole, and he backed it up with five further birdies in a sparkling five-under-par round of 67.
Bjerregaard has never won on the European Tour, but now at least looks set for a second appearance in the British Open, with the leading four from the top 12 this week who have yet to qualify to be given invites to Royal Troon.
He holds a narrow advantage over Belgian Thomas Pieters, but 23-year-old qualifier Mathieu Decottignies-Lafon gave home fans something to cheer with a three-under-par 69, although it could have been so much better.
The world number 1,051 only qualified for the main tournament at an event in Courson on Monday, but he looked set to share the clubhouse lead until he hit his second shot into the water on the 18th hole.
That meant a double bogey, but the Frenchman remains well-placed to beat his previous best finish of tied for 27th on the European Tour.
Former Ryder Cup winner Francesco Molinari is also on three under, alongside Decottignies-Lafon, England's Chris Hanson and Swede Magnus A Carlsson.
Victor Dubuisson, a better-known home favourite, had to settle for a 72 playing with McIlroy.
The 100th edition of continental Europe's oldest national open counts as two events on the Race to Dubai as well as providing double Ryder Cup points, as the European Tour attempts to compete with the PGA Tour event at Firestone Country Club.
Because of the Olympics in August, the Bridgestone was moved from its usual spot between the British Open and the PGA Championship, meaning a clash with the French Open this week.
Leading scores from the first round of the French Open at Golf National on Thursday (Gbr & Irl unless stated):
66 – Lucas Bjerregaard (DEN)
67 – Thongchai Jaidee (THA), Thomas Pieters (BEL), Bernd Wiesberger (AUT), Adrian Otaegui (ESP)
68 – Francesco Molinari (ITA), Mathieu Decottignies-Lafon (FRA), Chris Hanson, Edoardo Molinari (ITA)
69 – Sebastien Gros (FRA), Andy Sullivan, Brandon Stone (RSA), Romain
Wattel (FRA), Lasse Jensen (DEN), Joost Luiten (NED), Gregory Bourdy
(FRA), Mikko Ilonen (FIN)
71 – Rory McIlroy
74 – Lee Westwood
75 – Danny Willett