Gary Murphy, Bradley Dredge, Simon Khan and Sebastian Fernandez are in the clubhouse at 5-under-par 67.
Play was rolling along at Castello di Tolcinasco until a thunderstorm reached the area in the afternoon, ultimately forcing the suspension of the opening round. Francois Delamontagne is among the many who will return to the course to complete the first round early on Friday and the Frenchman had reached 5-under through 14 holes before play was stopped.
Fernandez-Gastano started on the back side and tallied back-to-back birdies from the 12th. He added a birdie at the par-5 15th and hit his approach to 3 feet for a birdie at the par-4 18th.
The 24-year-old ran home a 30-foot birdie putt at the par-5 first to reach 5 under, but he gave that shot back with a bogey at the par-4 sixth. Fernandez-Gastano then hit a tremendous drive at the par-5 ninth and knocked his second shot inside 4 feet for a closing eagle.
'I have been hitting the ball well the last couple of weeks, but the results have not been coming,' said the Spaniard. 'This is a tough course, very demanding off the tee especially and I just tried to be focused on every shot and not think about the result. I played some very good shots and I'm delighted with the round.'
Italian amateur Edoardo Molinari posted a 4-under-par 68 to join Marcel Siem and 1999 winner Dean Robertson two shots off the pace. Emanuele Canonica is at minus-4 on his round through 11 holes, while Malcolm Mackenzie and Jean-Francois Lucquin are at 4-under through 10 holes.
Defending champion Graeme McDowell collected four birdies and two bogeys to finish in a group at 2-under-par 70.