Ali Krieger, the 2003 All-Met Player of the Year while at Forest Park High, is shown playing for the U.S. national team against Japan last month. Next up: the Women’s World Cup in Germany. (Jamie Sabau/GETTY IMAGES)

On Tuesday night, Ali Krieger will join her U.S. Women’s World Cup teammates at Dulles International Airport for a flight to Germany, her de facto home for the past 31 / 2 years. The journey will fulfill a dream that began on the fields of Prince William County.

But if not for a decision she made late one night in January 2006, Krieger’s story might never have been told.

She had just returned to Penn State from her mother’s wedding, the maid of honor at the ceremony on Sanibel Island, Fla. Despite being on crutches, necessitated by surgery for a broken leg suffered two days before the start of the NCAA tournament, she celebrated with family, new and old.

But Krieger also strained to fill her lungs, an elite athlete powerless to accomplish the most fundamental function.

The problem refused to subside, so when she returned to campus, Krieger arranged for a check-up the next morning. The puzzling discomfort could wait overnight, she figured.

Her halting breathing pattern and irregular heart rate, however, alarmed her then-boyfriend, football player Brent Wise, a pre-med student. Krieger went to Mount Nittany Medical Center — a decision that might’ve saved her life.

“The doctors said if I had fallen asleep that night,” the 26-year-old defender recalled last week, “I most likely wouldn’t have woken up.”

Test results revealed blood clots in her lungs, causing a pulmonary embolism and a half-dozen small heart attacks. Without immediate treatment, such conditions result in death to about one-third of those afflicted. Barely 21 years old, one of American soccer’s most promising young players was in critical condition.

“I got a call at 2:45 in the morning from my ex-wife and she said you need to get to Penn State now,” said Ken Krieger, her father. “I was out the door at 2:50.”

With a heavy dose of blood-thinners, Ali’s condition stabilized. She remained hospitalized for a week, then began a regimen of self-administered injections for six months. Worst of all: no physical activity.

But Krieger was soon back on the field for her senior season at Penn State, and her soccer odyssey will continue at the World Cup for the U.S. national team, which is seeking its first world title since 1999. The 16-nation tournament will begin June 26 in Germany, a venue that fuses her pro and international careers.

‘I was always around it’

Soccer was woven into Ali’s upbringing in the Montclair section of Prince William County. Her mother was a physical education teacher, and her father was a one-time professional soccer prospect who later became a highly successful coach at Hylton, Osbourn Park and Forest Park high schools before accepting a full-time position to run the 2,700-player Prince William Soccer Inc. youth club three years ago.

“We were constantly playing: in hallways, in the basement, out in the front yard, in the street,” said Ken, who also had assistant stints at American and George Mason and worked with the D.C. United and Washington Freedom youth teams.

For 12 years, Ali played club ball with the same core of eight players on the Prince William Sparklers, coached by her father. On the high school level, she spent one year at Hylton before transferring to the newly opened Forest Park.

“My dad has always played and coached, so that’s what I knew,” she said. “I played other sports but always turned toward soccer and had the same love for it as my father. They never forced me to play; I always wanted to. I was always around it.”

On the field, Krieger excelled. “As a phys ed teacher, I realized she had something special,” her mother said. “I thought, ‘Hmmm, this could be interesting.’ ”

At Forest Park, she was an All-Met honorable mention as a sophomore, a first-team selection the next two years and, as a senior in spring 2003, was named The Post’s Player of the Year.

A troubling setback

Her next stop was Penn State, where she continued in midfield before moving to an injury-depleted backline.

In 2005, the unbeaten Nittany Lions were preparing for the NCAA tournament when Krieger fractured her lower leg in a workout, ending her junior season. A metal plate was inserted, and Krieger was relegated to crutches.

Despite her absence, Penn State advanced to the national semifinals in College Station, Tex. She was there when Portland ousted the Nittany Lions on penalty kicks. “I wanted to hop onto the field and take one,” she said.

The trip to Texas had been the first of several flights in a short period of time, which might have triggered the embolism. While air travel can slow blood flow, other factors came into play: the leg surgery, which could’ve allowed debris into the bloodstream; and her use of birth control pills, which include estrogen, a compound that can increase clotting. “A perfect storm,” she said.

She felt fine for a few weeks, finishing the fall semester and visiting her parents for Christmas break — dad in Manassas, mom in Florida. The day before her mother’s wedding, “Ali kept saying, ‘Mom, I can’t catch my breath,’ ” Debbie said. “She also said the back of her knee hurt. It was very weird.”

Krieger flew to Penn State, but the symptoms persisted. She would get to the bottom of it the next day, she thought. Wise, her boyfriend, checked her irregular pulse and recommended a visit to the hospital. After doctors examined her, “They were surprised I was standing,” she said.

Doctors attacked the clots with Coumadin, an anti-coagulant. After a week in the hospital, Krieger began her slow recovery. She missed the spring exhibition season and didn’t play over the summer, instead working at Penn State’s soccer camp. Doctors checked her regularly.

“My perspective changed. I was more motivated,” she said. “I knew I could fight back and get to where I had always dreamed.”

A new home in Germany

Wisconsin Coach Paula Wilkins, who guided Penn State at the time, said Krieger was unfazed by the challenge. “She was matter of fact about it: ‘I’ll just go through it,’ ” Wilkins said.

She did, and in her senior season she started all 19 matches and shared the team lead in assists (five). At that point, her pro prospects were murky, caught in the lull between the Women’s United Soccer Association’s demise in 2003 and Women's Professional Soccer’s lift-off in ’09.

After playing for the U.S. under-23 team at the Nordic Cup in Germany, Bill Irwin, the American coach, floated the idea of returning there to play professionally. Few U.S. women’s players had ventured overseas, but after enlisting a German agent and consulting with Grover Gibson, a former Hylton player who spent years in Germany’s lower divisions, she signed with FFC Frankfurt, one of the premier clubs in the Women’s Bundesliga.

In 2008, the club achieved a rare treble, winning the Bundesliga title, German Cup and UEFA Women’s Championship.

“Playing and living in a European soccer culture helped her understand and love the game even more,” said U.S. national team coach Pia Sundhage, who selected Krieger for the first time in 2008.

That year, Krieger suffered another setback: a foot injury that eventually led to a fracture. After recovering in 2009, she went on loan with the Washington Freedom of WPS. But her heart remained in Germany, and aside from periodic national team assignments, she spent almost all of her time there.

The World Cup will indirectly reunite her with many of her Frankfurt teammates who play for Germany’s powerhouse squad. Her expertise of German culture will provide guidance to the U.S. team, which will be based in Frankfurt. The city also will host the World Cup semifinals — which could feature the United States against Germany, the two-time defending champion — and the final.

“Out of all the places in the world,” Krieger said, “to have the biggest games in Frankfurt, the place where I’ve lived and loved, is amazing.”

She knows where to find the best tapas and pastries, as well as burgers at Die Kuh Die Lacht (The Cow Which Laughs). Her paternal roots passed through Berlin and her family name in German means “Warrior.”

She speaks the language fluently and sports a tattoo on her inner left arm that reads: “Liebe” — Love.

“It tells a story,” she said, “my German story.”