HARRISON, New York (Reuters) - Phil Mickelson showed signs he was returning to form by shooting a four-under-par 67 on yesterday to put his name on the leaderboard at the Barclays Classic.

Mickelson, whose promising season was derailed after he injured his left hand practising out of the deep Oakmont rough before the US Open, made four birdies on his second nine holes to stand two shots behind early leader Brian Gay.

"It's nice to get off to a good start here," said Mickelson, who posted his lowest score in a US Tour event since opening with 67 on his way to winning The Players Championship in May.

"It was nice to shoot a few under par and get off to a good start in the first play-off," he told reporters at the first of four tournaments that comprise the new season-ending FedExCup series.

The 37-year-old Mickelson, ranked third in the world, missed the cut at the US and British Opens and only earlier this month became able to hit the ball without putting on a patch to numb the pain he felt in his hand.

"I started striking the ball well a couple of weeks ago. I felt like I was going to start playing well and I struggled with the putter," he said.

"The front nine (today) I struggled with the putter but the back nine I made a good round of it. If I can start to getting a little more confidence on the greens, that should hopefully help me shoot lower scores."

Mickelson says he is motivated and eager to do well in the season-ending push culminating in the Tour Championship.

"My excitement level to play golf is very high," he told reporters on the eve of the tournament.

"I feel like I've been suspended for three months. My hand feels great now and I'm able to practise fully. I feel like my game is getting sharp."