By Mark Lamport-Stokes

PACIFIC PALISADES, California (Reuters) - Former world number two Phil Mickelson has already achieved far more on the golf course than most of his peers but the 41-year-old American says his work is far from done.

"I want to try to win more tournaments and more major championships. I love competing. It's been frustrating when I haven't been in contention," Mickelson told reporters at a rain-sodden Riviera Country Club on Wednesday.

"It's a lot more frustrating for me to finish 25th than it is to finish second at the British Open where I came so close and let it slip away."

Mickelson tied for second in last year's British Open at Royal St George's, having charged into a share of the lead with a stunning start to the final round before slipping back.

"I would much rather have that where I'm in the thick of it, have that excitement level," said the Californian, who has yet to win a British Open. "That to me is what I really enjoy.

"And so the motivation is I want to get those opportunities. I want to have more of those opportunities and see if I can finish them off."

Short game magician Mickelson, who fired a flawless eight-under-par 64 to win the Pebble Beach National Pro-Am by two shots on Sunday, did not expect any letdown in his play at this week's Northern Trust Open.


"I had such a fun week (at Pebble Beach) that I want to try and have that again," said Mickelson, who was six strokes behind going into the final round at Pebble Beach and outscored his playing partner Tiger Woods by a remarkable 11 shots.

"I don't feel like there's a letdown, there's an excitement and a new energy to get back in that position. I know I was six back, but I felt like I was right in it starting the last day.

"I'm playing well and if I play my game and focus hard, I should be able to get in contention and have that excitement again," added the American, who triumphed here in 2008 and 2009.

"It's where I want it to be, and we're just making sure that it stays there, that there's no major changes (in) what we will be doing," the world number 11 said.

"It's more just going back to the fundamentals for (Harmon) and I, getting a good foundation and then getting ready to compete. I have a pretty good understanding of how to play Augusta National, so it's not like I'm looking for any answers.

"I know how I want to attack it given each pin placement ... the shots I want to hit, and now it's just a matter of refining and getting ready so that it's there when I need it."

Mickelson won the Masters in 2004, 2006 and 2010.

(Reporting by Mark Lamport-Stokes; Editing by Frank Pingue)