It gave the 2004 Masters winner a three-under par 67 and tied him for the lead with American Ben Curtis, South Africans Trevor Immelman and Rory Sabbatini, Australia’s Stuart Appelby and Canadian Stephen Ames.
Stacked up only one shot behind them was a group that included Germany’s Bernhard Langer, American Davis Love, England’s Greg Owen and Australia’s Steve Elkington.
It was exactly the start Mickelson wanted as he attempts to salvage his year after failing to make any impression in the season’s earlier Majors - the Masters, the US Open and the British Open.
Curtis’ 67 was welcome relief for the 28-year-old who has been struggling with his game since his surprise British Open victory two years ago.
In 16 outings this season, he has only made the cut three times.
Immelman puts down his good showing at Augusta and the British Open for his impressive first round and said three-under was a good score on a course that has no weaknesses.
Vijay Singh kept himself in touch when he birdied the last two holes to get himself back to level par.
But Tiger Woods, who was expected to be in a two-way battle for the title with Singh, slumped to a five-over 75 and has his work cut out to ensure his place at the weekend.
England’s Ian Poulter birdied the last three holes to put himself one-under for the championship.
There was no such joy for Colin Montgomerie. The Scot go himself to one under but suddenly lost him game as he crashed to end the day seven-over par.
First round scores
67 - Trevor Immelman 33-34, Ben Curtis 33-34, Stuart Appleby 34-33, Phil Mickelson 34-33, Rory Sabbatini 35-32, Stephen Ames 35-32
68 - Steve Elkington 31-37, Bernhard Langer 32-36, Heath Slocum 34-34, Greg Owen 35-33, Davis Love 35-33, Lee Westwood 34-34, Retief Goosen 35-33, Jesper Parnevik 35-33, Pat Perez 32-36, Ben Crane 32-36, John Rollins 32-36
69 - Ian Poulter 36-33, Ted Purdy 34-35, Hal Sutton 34-35, Justin Leonard 34-35, Luke Donald 35-34, Tom Pernice 35-34, Kenny Perry 38-31, Fred Funk 36-33, Geoff Ogilvy 33-36, Mark Hensby 35-34
70 - Charles Howell 36-34, Mark Calcavecchia 34-36, Jerry Kelly 36-34, Kevin Na 35-35, Zach Johnson 35-35, Steve Flesch 33-37, Bo Van Pelt 36-34, Carlos Franco 34-36, Paul Casey 35-35, Vijay Singh 35-35, Alex Cejka 35-35, Dudley Hart 35-35.
MOSCOW: England’s up-and-coming Tom Whitehouse showed true grit to take a one-shot lead in the European Tour’s Russian Open on Thursday with a superb six-under-par 66.
Whitehouse had to endure pain for the first nine holes after waking up with a freak wrist injury, and despite the drizzly conditions he finished with a one-shot lead on Spains Jesus Maria Arruti, Scotlands David Drysdale, Swedish pair Mikael Lundberg and Fredrik Widmark and two-time tournament winner Iain Pyman of England.
The 25-year-old Englishman admitted ironically he had been watching Scotland’s Colin Montgomerie on television on Wednesday explaining his own wrist injury.
Leading scores
66 Tom Whitehouse
67 Jesus Maria, David Drysdale, Mikael Lundberg, Iain Pyman, Fredrik Widmark
68 Jose Manuel Carriles, Ben Mason, Shaun Webster, Craig Williams
69 Stephen Browne, Bertrand Cornut, David Dixon, Jeppe Huldahl, Hernan Rey.—Agencies