Phil Mickelson flirted with the 11th sub-60 round in the history of the PGA Tour on Thursday before settling for a 12-under 60 at La Quinta Country Club in the first round of the Desert Classic in California.

He holds a three-shot lead over Adam Long, who sits in second place after shooting a 9-under 63 at PGA West's Nicklaus Tournament Course.

"It was kind of a lucky day for me in the sense that I did not feel sharp coming in," Mickelson told The Golf Channel after his round, referencing his tweet prior to the round that he was feeling "rusty." "I did not have the intense practice sessions that I would have liked, but I felt like all parts were OK and it just clicked. ...

"It was a fun day. I certainly did not expect this to be the case, but I'm also excited to start the year, so I was fresh."

Taking advantage of the easiest course on the PGA Tour last season, Mickelson birdied his first two holes and made the turn in 6-under 30. He then reeled off five more birdies over his next seven holes to set up his chance at the elusive 59.

Needing to birdie the final two holes -- both par 4s -- Mickelson parred the 17th before rolling in a birdie on his final hole. It marked the 37th round of 60 on the PGA Tour and the third of Mickelson's career. His two previous 60s came at the Waste Management Open in Phoenix, but TPC Scottsdale is a par-71 course.

"I came to the realization (regarding the possibility of shooting 59) on 16 when I had that putt for birdie that if I make that 4-footer and birdie the last two, I would shoot 59 and I gave myself a decent chance," Mickelson said. "The shot on 17, I was trying to hook a sand wedge and kind of get that thing to side spin towards the pin, and I just didn't hook it enough. I still had a good look at it, but I just didn't roll that one in."

The Desert Classic is a pro-am format, with players rotating among La Quinta, the Nicklaus Tournament Course and the Stadium Course, the latter two at PGA West, over the first three days. All three courses are par 72. Sunday's final round will be played at the Stadium Course.

La Quinta yielded the lowest average score (68.831) of any par 72 on the PGA Tour last season. The Nicklaus Tournament Course was No. 2 (69.445), while the Stadium Course yielded an average of 71.181.

Mickelson, a two-time winner of the Desert Classic (2002, 2014), did his best to take advantage of the La Quinta course in soft conditions on Thursday. He will play the Nicklaus course on Friday and the Stadium Course in the third round and noted that the pressure was on to perform in Round 2.

"It's very difficult to start out with a round and go low like this and then follow it up because the expectations are (that) anything short of a victory is a failure," said the 48-year-old. "Yet we have three full rounds on some challenging golf courses with a lot of potential birdies, so it's a tough position to be in but it's one that I thoroughly enjoy."

Australia's Curtis Luck sits alone in third place at 8 under after his round at La Quinta.

Trey Mullinax (Nicklaus), Wyndham Clark (La Quinta), Canada's Adam Hadwin (Stadium) and Scotland's Martin Laird (Nicklaus) are tied for fourth at 7 under.

Spain's Jon Rahm, seeking to join Johnny Miller (1975-76) as the only repeat champions of the event, shot 6 under at La Quinta, leaving him in a 10-way tie for eighth place. Rahm beat Andrew Landry on the fourth hole of a sudden-death playoff last year.

Reigning FedExCup champion Justin Rose is the first No. 1-ranked player to compete in the Desert Classic since the world ranking system began in 1986. The Englishman shot 4 under at La Quinta on Thursday, good for a tie for 31st.

Charlie Reiter, who missed the cut as a high school senior last year, is in the field again on a sponsor exemption. Reiter, currently on the University of Southern California team, shot 3 over par at La Quinta on Thursday, better than just eight golfers in the 156-player field.