Jason Norris is one of 11 players one shot back from the lead after the first round of the Spanish Open.
The 45-year-old Victorian opened with a birdie and added another four throughout his round to sit five-under-par alongside a group including hometown hope Jon Rahm and Spanish amateur Victor Pastor.
Scotland's Marc Warren finished with five birdies in the last seven holes to lead at six-under alongside Paul Dunne of Ireland.
World No.4 Rahm is the main attraction at the tournament after coming fourth at the Masters last week. He is looking to make amends for his late slip-up in Augusta, when he blew his chance by finding the water on the 15th on the final day.
Rahm had a birdie at the 13th before a bogey at the next hole but signed off on a high with an eagle at the 18th.
"To be honest, I played a lot better than I expected, especially off the tee," Rahm told the European Tour website.
"My driver was really good today – the driver alone set up two birdies, on 13 and on 7. Things like that are obviously a bonus. Too bad I couldn't make a couple of putts but I guess it's happening to everyone, the greens are not easy to read."