Playing with the tournament namesake's grandson, Rafa Cabrera Bello fired a 7-under 65 on Thursday to claim a two-shot lead after Round 1 at the Arnold Palmer Invitational in Orlando, Fla.

In a threesome with Kevin Streelman and Sam Saunders, Palmer's grandson, the Spaniard claimed his first post-round solo lead on the PGA Tour since he turned pro in 2005. The 34-year-old, who is ranked 34th in the world, has five international victories but is still seeking his first on the PGA Tour.

Keegan Bradley is in second place alone after shooting 67 at Bay Hill Golf Course, with Phil Mickelson, Bubba Watson, Billy Horschel, Patrick Rodgers and Northern Ireland's Graeme McDowell sharing third place at 4 under.

Six players sit at 3 under, including world No. 10 Francesco Molinari of Italy, who made one of two aces on the day at the par-3 seventh.

Cabrera Bello started his round on the back nine with four birdies in his first six holes. After a blemish at No. 1, he rattled off four more on the next five holes before parring Nos. 7-9 to cap his round.

"He's the perfect case of ignorance is bliss," Saunders told The Golf Channel. "He doesn't know how hard this golf course is supposed to be. He made it look awfully easy today."

"I really didn't know what to expect," Cabrera Bello said after his round. "I know how nice and tough the course is, and I think it's a course with many, many daunting shots. So I feel the more you play it, probably the better. So I wasn't really having much high expectations as opposed to just getting out there and playing my golf."

Bradley, who finished second at the event in 2014, put together a bogey-free day after also opening on the back nine. His round was highlighted by three straight birdies at Nos. 4-6.

Mickelson, the 1997 champion, bogeyed his second hole before also ripping off three straight birdies at Nos. 4-6. After another birdie at No. 9, disaster struck with a double-bogey at No. 10, after the left-hander played a right-handed shot -- with his club upside down -- near a mesh fence. Mickelson rebounded with three more birdies, including one after dropping his approach to a foot away at No. 18.

"I actually thought I could get it on the green, I really did," Mickelson said afterward of his righty shot, which wound up right back at his own feet. .".. It obviously didn't work out."

Defending champion Rory McIlroy of Northern Ireland is tied for 49th after shooting even par.

Tiger Woods, an eight-time winner of the event, is not in the field this week after withdrawing due to a neck strain.