Frenchman Grégory Bourdy set the clubhouse target at the Iberdrola Open in Mallorca with a course record seven under par 63.
Bourdy started on the back nine and fired five birdies in an outward 31 before four more coming back gave him a one shot lead over England's Danny Willett.
Bourdy is targeting a first European Tour win since his victory at the UBS Hong Kong Open in 2009, having finished second at the Maybank Malaysian Open last month.
"It's always great to hold a course record," said three-time European Tour champion Bourdy. "It's very nice on Tour to get a score like this.
"I made nine birdies, only two or three mistakes but it was a wonderful day."
Northern Ireland's Darren Clarke, who claimed the last of his 12 European Tour victories at the KLM Open in 2008, shot four birdies in his final nine holes to reach five under for his first round, good enough for third place ahead of the afternoon starters beginning their rounds.
Welshman Rhys Davies is one further back at four under, hoping to add a second European Tour title to his victory at the Trophée Hassan II in Morocco last year, while Scotland's Scott Jamieson was in a tie for fifth alongside Chris Wood, although the Englishman had one hole still to play.
There were some great shots as well as great rounds - Norway's Eirik Tage Johansen and New Zealander Mark Brown both managing a hole in one at the par three 13th.
Among the afternoon starters were double Masters Tournament champion and Ryder Cup Captain José Maria Olazábal and his predecessor Colin Montgomerie - both of whom had flown in from Pedreña having attended Seve Ballesteros' funeral on Wednesday.