McGowan, whose lone European Tour victory was in Madrid two years ago, leads Brett Rumford of Australia, Lorenzo Gagli of Italy and Gonzalo Fernandez-Castano of Spain. Defending champion Luke Donald of England was four shots behind after shooting 68.
The 29-year-old McGowan, ranked No. 492, carded 10 birdies in total – including five in succession from the ninth hole – for his best European Tour round in three years.
“I think I like Madrid. That was a much better round than I’ve been putting together recently,” McGowan said. “I got off to a good start, birdied the first two, and just kept trying to hit good golf shots, that was the key. I kept finding the right spots on the greens and holing the putts,” added McGowan, whose impressive form comes with his European Tour card for next season in danger.
“It’s been a pretty tough year with a couple of injuries but it’s been improving week to week and this week it really seems to have come together.”
Donald felt his opening round at the El Encin Golf Hotel course could have been better.
“I felt like I left a few out there,” Donald said. “A couple of careless mistakes but a lot of solid golf in there too.”
Gagli finished with three birdies to join Rumford and Fernandez-Castro in the chasing pack on 7 under, with Italian Ryder Cup player Edoardo Molinari further shot back after shooting 66.