Phil Mickelson shot a superb four-under-par 68 in the second round of the Masters to put himself on course for a third Green Jacket in five years.

The World number two - champion at Augusta in 2004 and 2006 - is three shots off the halfway pace set by Trevor Immelman.

"I feel pretty good," said the 37-year-old Californian. "I would rather be leading. I would like to have some shots in hand."

But the left-hander is happy with his game heading into the weekend, adding: "I've hit the ball well, and I've been playing well.

"I'm only a couple shots off the lead, and I'll be able to play late in the afternoon on Saturday and hopefully on Sunday as well.

Mickelson opened with birdies on two and three to move up the leaderboard and an eight-footer at the par-five eighth took him through the turn in three-under 33.

A run of eight straight pars followed, including a missed four-footer for birdie on the 15th. But he made up for that with a long putt for birdie at the 17th to come home in 35.

The tournament is taking on a familiar shape for Mickelson, who was fifth at the halfway stage in 2004 and fourth on Friday evening two years later.

"At least I am working in the right direction, but I've got a long ways to go and there's a bunch of players ahead of me, and a bunch of strong players right behind me," he added.

"I think it's going to be an exciting weekend."

Mickelson has rode his luck over the first two days. Twice he has narrowly avoided landing in the creek with his second shot at the par five 13th, making a birdie in the opening round and a par on Friday.

"I'm kind of using that as an omen," a smiling Mickelson told reporters. "I've hit two shots now, yesterday and today, that should have been in that creek and both of them stayed up."