Stevens quickly signed Kerr as a client; within the year she was pulling in new sponsorship contracts, including Mutual of Omaha, which signed her in 2003.

The following year, was one of mixed blessings. Kerr's career took off: She won three tournaments and finished as the No. 2 player in the world, behind Sorenstam. At the same time, her mother was diagnosed with breast cancer, dealing Kerr a painful lesson in the preciousness of life. Starting Birdies for Breast Cancer was her way of dealing with her mother's illness and educating others as well.

When Kerr and Stevens started dating in 2005, Kerr began spending more time at Stevens' apartment on Manhattan's Upper East Side. Indeed, New York City gets part of the credit for Kerr's transformation.

"Going to museums, shopping on Madison Avenue, eating in great restaurants—it all seemed to make her realize 'Hey, this is where I belong,'" Stevens says. "She was growing more sophisticated and more confident before my eyes."

Kerr agrees.

"Being in New York helped me as a person. I love it—all the hustle and bustle. It's a cultural mecca. The city has exposed me to art, wine and all the finer things that have shaped my life."

The couple counts among their friends the managing partner of upscale restaurant Nobu, Richie Notar; hockey great Wayne Gretzky; one of the founders of MTV and a former chief of AOL Time Warner, Bob Pittman; and Trump. ("People see him on TV and he comes off as so intimidating," Kerr says of The Donald. "But when you're close to him, he's so cordial, a kind, nice guy.")

When she and Stevens went looking for a money manager, a colleague in the sports marketing world introduced the pair to Alan "Ace" Greenberg, the ex-chairman of the investment company Bear Stearns. They hoped he might recommend someone, but Greenberg was so taken with Kerr, Stevens says, that he offered to be her personal financial counselor.

"Cristie has a lot of charisma," says John Hildenbiddle, Mutual of Omaha's senior vice president for brand management. "She's great at the client events we hold at tournaments, and she has a kind of personal swagger that we find very appealing."

Chris Keane / Reuters Cristie Kerr's game, and life, took off when she got serious about her fitness.

Kerr is a well-loved figure around the Mutual of Omaha home offices. When she finishes in the top three of a tournament, the company contributes $1,000 to Birdies for Breast Cancer and an employee is selected to receive $1,000 for the charity of his or her choice.

Kerr says there are two sides to her professional life: one "between the ropes" as a player, the other in the business world. Learning the ways of the second was harder than those of the first.

"By nature I'm a private person," she says. "I'm intense when I play, and people can misconstrue that. But the reality is that you always have to make the best part of your personality come across. Being exposed to amazingly successful people has made me appreciate the intricacies of the business world. I've learned so much from them."

Kerr and Stevens are quick learners. The couple has devised a strategy of building Kerr's endorsements around her interests.

"We're branding Cristie using the things she likes—art, wine, jewelry, real estate—to insert her into the luxury category," says Stevens. "It only makes sense to have a woman representing big-ticket goods: Marketing research shows that women are the real decision makers."

The plan seems to be working. According to Stevens, Audemars Piguet did extremely well with the Ladies Millenary watch that Kerr wore in an ad, which ran in magazines such as Vanity Fair. And Kerr has been investing in Arizona real estate, which Stevens is using as a platform to form an endorsement deal with a major Western bank.

"The top 10 LPGA players get sponsorships well into six figures; the top five get seven-figure deals," Stevens says. "Cristie is a seven-figure player."

The fruits of Kerr's success—present and prospective—reside at a gracious golf community called Mirabel, located in the desert north of Scottsdale. Kerr and Stevens divide their time between a New York City apartment and Mirabel, where I meet them in late December.

They have just flown in from Telluride, Colo., on NetJets, the time-share executive aircraft fleet which Kerr promotes in what amounts to a "miles for smiles" arrangement. It beats commercial travel, but even with private aviation, there can be glitches: On Nov. 13, at the Wendy's 3-Tour Challenge, she, Natalie Gulbis and Morgan Pressel competed against three PGA Tour players and a Champions Tour team. Kerr won the event for the LPGA Tour team by holing a five-foot birdie putt on the first playoff hole, after which they were scheduled to depart on a Wendy's corporate jet. But it developed mechanical problems on the tarmac and the trio arrived at the next week's tournament a day late.

Kerr and I catch up at Mirabel's clubhouse, a vast, Frank Lloyd Wright style building with a restaurant, spa and pro shop. The airy, open-beam central room has a baronial feel. Stevens, whose work is never done, is on his cell phone, hammering out a sponsorship package with a luxury automaker. Kerr, enjoying her off-season, is making catering arrangements for a holiday party at the couple's house.

Kerr and Stevens live in a newly built, three-bedroom stone and stucco house. As we enter, she points out her equipment room. A glance inside reveals enough golf merchandise to stock a small shop.

Kerr then leads me into her pride and joy: the wine storage room, where she keeps approximately 1,000 bottles, about three-quarter reds, in cooling units at a temperature between 54 and 57 degrees.

"I'm not a collector," she says. "We rarely keep bottles for more than two years. We buy wine to drink it."

Maybe it's the sight of all that vino, but when Kerr ushers me into the spacious great room—which contains the living and dining areas and the kitchen—my first thought is, "What a place for a party."

The house is decorated in a style that could be described as "Southwestern -lavish-comfortable." The rooms have deeply padded leather seating along with brawny Spanish Colonial furnishings detailed with turquoise inlays and hammered-copper tabletops. Kerr has accented these pieces with Oriental rugs, intricate dried floral arrangements and colorful contemporary Western art.

"Most of the furniture is so dark and heavy, I wanted to have something bright on the walls as a contrast," she explains.

The U.S. Open trophy, Kerr's to keep for a year—"Unless I win it again," she says, in a tone that suggests she means to do exactly that—rests on a stand in a modest anteroom. Pride of place is instead given to a luminous oil painting by the noted artist Jim Norton, which hangs above the fireplace. The picture depicts a group of mounted cowboys on a ridge above a valley.

Their horses' hooves are kicking up a fine haze of dust. The men look as if they have come far and may have a long way to travel. But there is a stern look of purpose in their eyes: They are on a mission, and, just like Kerr, they know precisely where they are headed.