Updated

By Mark Lamport-Stokes

LOS ANGELES (Reuters) - When Phil Mickelson tees off at next week's Colonial Invitational at Fort Worth in Texas, the American left-hander will have another chance to replace Tiger Woods as world number one for the first time.

Woods, who has steadily dropped ranking points this year, is sidelined with a lingering neck injury and Mickelson would take over at the top should he secure victory at Colonial Country Club, a venue where he triumphed in 2000 and 2008.

"A win for Phil would do it," Ian Barker, the European Tour's director of information services who manages the official rankings, told Reuters on Thursday.

"However, second place alone would almost certainly not be enough unless the field at the Colonial is considerably stronger than last year."

A fortnight ago, second-ranked Mickelson had an opportunity to dethrone the 14-times major champion at the Players Championship in Florida. Victory, with Woods finishing outside the top five, would have done the trick.

Although a battling Woods failed to finish the tournament, pulling out of the final round because of neck pain, Mickelson failed to deliver his side of the bargain.

Five shots off the pace after round three, he signed off with a topsy-turvy 74 to slip back into a tie for 17th at the prestigious event dubbed the unofficial fifth major.

Overall, though, Mickelson has been the game's standout player over the last nine months and, in the eyes of many, a deserving world number one.

He ended his 2009 campaign in barn-storming fashion, clinching the PGA Tour's season-ending Tour Championship in September and the WGC-HSBC Champions in China in November after overshadowing Woods in each of those high-profile events.

EXUDED CONFIDENCE

Since returning to the U.S. circuit for this season, short game magician Mickelson has exuded confidence with his driving under much more control and his putting in tip-top shape.

Although his early results were not what he wanted, he peaked at the best possible time to claim his third Green Jacket at last month's U.S. Masters before finishing second at the Quail Hollow Championship.

"Taking some weaknesses and turning them into that strength gives me the confidence or the belief that this could be an exceptional year," he told reporters.

"I was putting well at the end of last year but in the last three years I've taken what has always been a weakness in my game -- driving -- and I've turned it into a real weapon."

While Woods's stock has plummeted since his private life unraveled at the end of 2009 amid allegations of marital infidelities, Mickelson's fortunes have soared.

Claiming the number one spot in the rankings would fill one of the few remaining gaps in Mickelson's glittering resume.

"It's certainly something that I have been striving for but have not achieved yet, so it would mean a lot to me," he said before this month's Players Championship at Sawgrass.

(Editing by Frank Pingue)