Yankee fans are no strangers to odd turnabouts.

Lou Gehrig died on the anniversary of the day he replaced Wally Pipp at first base. In 2001, the Yankees lost the World Series after being dubbed “America’s Team.” A couple of weeks ago, on Jackie Robinson Day, the only active player in the Majors still wearing Robinson’s no. 42 — Mariano Rivera — gave up a walk-off home run and the Yankees lost.

Another involves Cristyne Nicholas, who often is seen sporting a Yankees hat. For Nicholas, the problem is that while the Yankees are in her heart, it is the Red Sox — specifically pitcher Daisuke Matsuzaka — that contribute to her bottom line. She’s wondering what kind of welcome she’s going to get in the Bronx this weekend when her beloved Yankees take on the hated Red Sox.

“I love New York but Boston is a client,” she says, sitting in her new office overlooking Rockefeller Center. After leaving the organization whose mission it is to promote New York, NYC & Company, to start a PR and consulting firm, Nicholas & Lence, the first client she signed was the Greater Boston Convention and Visitors Bureau.

So, for Nicholas, who was born in Brooklyn, grew up on Long Island, and spent some 15 years being one of the city’s most recognizable faces first as press secretary and communications director for Mayor Giuliani and then as the president and chief executive officer of NYC & Company, this is going to be a weekend of divided loyalties.

“The Red Sox had just spent a fortune signing Daisuke Matsuzaka and they knew what we had done here in New York when the Yankees had signed Hideki,” Nicholas says. “They wanted to know if I could do the same for them.”

Hideki is Hideki Matsui, the Yankees outfielder who attracts visitors from Tokyo as easily as the Met brings in opera lovers.

NYC & Company had been exploring ways to increase the number of Japanese visiting the city when it heard the Yankees were looking to sign Matsui. Working with the Yankees, NYC & Company used the outfielder in a series of promotional videos and advertisements that ran in Japan. The result was immediate.

Over the course of a year, the number of Japanese visiting New York jumped 66%, bringing in an estimated additional $50 million into New York’s economy.

The number of Japanese visitors to New York has increased ever since.

Since signing the Boston Convention and Visitors Bureau, Nicholas and partner George Lence have more than doubled the size of their operation, signing more than a dozen clients and having many more deals in the works.

Nicholas insists there’s no real conflict between helping Boston and loving New York.

“Tourism transcends some of these things,” she says. “If we get visitors to Boston, they can then come down to New York and if we get them to New York, they can also visit Boston.”

In the meantime, she’s looking forward to the Red Sox visit and hopes she’ll get to see Matsuzaka pitch.

“I’ll be there,” she says. “And I’ll be wearing pinstripes.”

cminer@nysun.com