Mickelson back on his game at BMW Championship

The morning fog lifted at Conway Farms, and then Phil Mickelson's mental fog vanished just in time for him to make a late-season push and show everyone he's physically healthy as well.

And now this is clear: The 47-year-old crowd favorite is playing his best golf of the season.

"It feels great to be able to have energy throughout the round and keep my focus up," Mickelson said following his bogey-free 66 on Thursday in first-round play of the BMW Championship, the penultimate leg of the FedExCup playoffs in sunny Lake Forest.

"I'm really excited with some simple changes I've made in the last month to get my game back."

Mickelson, who carded 5 birdies, is tied for 10th but just 4 shots behind leader Marc Leishman, who took advantage of perfect weather conditions to fire a 9-under 62.

The Aussie, who admittedly has been streaky throughout his career, parred the last three holes. Two strokes behind Leishman and tied for second are Jason Day, Charley Hoffman and Jamie Lovemark. A total of 48 players broke par.

Defending champ Dustin Johnson carded an even-par 71 (tied for 49th).

Leishman was 7-under through 11, giving him a realistic shot to match the 59 Jim Furyk fired at Conway Farms in the 2013 BMW Championship. He had been down this road before.

"Today, (shooting 59) entered my mind for a little bit," said Leishman, who birdied 10 of the first 15 holes. "The time that I thought about it before was in New Orleans a couple of years ago. I got a bit greedy and ended up bogeying a par 5."

Leishman is coming off a third-place finish in the Dell Technologies Championship at TPC Boston, where Mickelson also played well.

He tied for sixth, his best finish in any stroke-play event this year. Mickelson has battled fatigue this year to the point where he has spent multiple days at a time in bed. He described his state of mind as a "mental fog," which affected his game, tee to green.

"I mean, it's been only five rounds," Mickelson said. "But after Boston I feel the momentum is starting to kick in."

Mickelson closed with a birdie on the 589-yard par-5 18th, which played into a slight breeze, smacking a 3-wood approach into the greenside bunker. He then deftly hit a sneaky downhill lie to 7 feet and drained the putt, all part of the "visualization" he had been lacking.

He also had a par-saving putt on the 16th from about the same distance, after an errant tee shot.

"One of the things I've really struggled with on the greens is getting connected to the hole," Mickelson said.

Fog delayed the start, but once play began players had little problem making birdies.

Rickie Fowler, tied for fifth at 6-under, birdied six straight holes before missing a 13-footer on No. 18 and settling for par. After he left his tee shot short on the par-3 17th, he chipped in from 64 feet. He drained a 20-footer on the 13th.

Day, who won here two years ago with a staggering total of 22-under, birdied three of the last four holes and also eagled the eighth.

"It's a great golf course," said Day, who switched his caddie and putter before the tournament. "It sets up nicely for me."

The golf course set up well for nearly the entire 70-player field. Only four golfers shot worse than 3-over par. Leishman is among many whose confidence is soaring heading into round two, which is expected to bring similar warm weather.

"It makes the game easier when all you're thinking about is making birdies," said Leishman, who sank putts of 21 feet on No. 9 and 19 feet on No. 11. "When your confidence is low and you're not putting as well or striking the ball as well, you might not be thinking about birdies."