Pia Sundhage, coach of the U.S. women's national soccer team, sometimes sings to relax her players. (RALPH ORLOWSKI/REUTERS)

In the tense hours leading up to the Women’s World Cup final here on Sunday evening, Pia Sundhage has had a song in her heart. All that’s left is the final verse.

Sundhage’s calming influence is a big reason why the U.S. women’s soccer team is on the verge of its first World Cup title since 1999. She said she will sing anything to help her players combat stress, but admits to a fondness for Simon and Garfunkel.  

And then — in case there were any doubters at a news conference on Friday — the melodic Swede started belting out “The 59th Street Bridge Song (Feelin’ Groovy).”

The Americans have traveled a somewhat rocky road to Sunday’s final against Japan, suffering a 2-1 loss to Sweden in group play (their first loss in an opening round of the World Cup) and needing a miraculous header from Abby Wambach with almost no time left to force a penalty-kick shootout in a win over Brazil in the quarterfinals.

Sundhage, 51, insists it’s “something about the American attitude” that has propelled her team through adversity. Her players, however, said their coach’s ultra-positive outlook is of equal importance.

Here are some of her oft-quoted phrases: “My glass is half full”; “I coach what is healthy”; “if you have positive expectations, it very often happens.” When asked how she is, she responds with a chipper “Excellent!”

On Saturday, Sundhage said she would prepare her team by showing videos of previous goals and highlights from past games, including the three U.S.-Japan matches earlier this year, all won by the United States.

The effect, U.S. midfielder Heather O’Reilly said, is that it “allows us to take more risks on the field because we have seen success over and over.”

“That feedback, I hope, will make them stronger, gain some confidence, and I’m also telling them, ‘This is good, do it again,’ ” Sundhage said. “It’s fun for me to coach like that.” 

Sundhage’s optimism is infectious, and it gives her charges greater confidence in her coaching decisions.

“She is the most positive coach I have ever had,” said O’Reilly, who explained that when she was moved from striker to midfielder, it was Sundhage’s enthusiasm about “the energy that I could give on the outside” that got her on board.   

Midfielder Megan Rapinoe was in the starting lineup prior to the World Cup but didn’t complain when she found herself on the bench for the sport’s biggest event.

Instead, Rapinoe has lit up the tournament with her remarkable energy as a substitute.

Sundhage became the first non-American coach of the women’s team in 2008, following coaching stints in Philadelphia and Boston in the Women’s United Soccer Association, the professional league that existed from 2001 to 2003.

At the time, the national team was licking its wounds after its ignominious exit from the 2007 World Cup. In a much-publicized outburst, U.S. goalkeeper Hope Solo criticized the decision of then-Coach Greg Ryan to bench her for a semifinal game against Brazil. The United States lost, 4-0, and Ryan banished her from the team.  

Sundhage said one of her first priorities as coach was strengthening the team’s defense, including goalkeeping. She brought back Solo, who played a key role on the United States’ gold medal-winning team at the 2008 Beijing Olympics.

Sundhage has tried to instill, with limited success, a technical mastery of the game rather than a reliance on pure athleticism and power, which is largely how the Americans finagled their way into Sunday’s final.  

“We’re still working on it,” admitted Wambach, who noted that their wins against France and Brazil relied less on intricate skill and more on “gutsy soccer, American soccer, win-at-all costs soccer.”

Sundhage grew up in the Swedish countryside in the 1960s, when it was taboo for girls to play soccer.

But Sundhage cut her hair, started calling herself Pelle (a boy’s nickname) and began playing on boys’ teams.  

She became a Swedish soccer sensation. She played in her first game with the national team at age 15 and represented her country in two World Cups. In the late 1980s, she was featured on a Swedish postage stamp.

“She was the first big Swedish superstar in Swedish soccer, but not always accepted by all Swedish people because football was such a man’s sport,” said Anja Gatu, the sports editor for Sydsvenskan, a Swedish daily newspaper.

But as stereotypes broke down, Sundhage’s status in Sweden rose to a national treasure, helped in no small part by her “very happy, very relaxed, very spontaneous” attitude, Gatu said.  

It’s that lighthearted mentality — that tendency to break into song at a moment’s notice — that has kept things loose during tense moments.

“She’s always positive, her glass is always full and that helps to stabilize the team in moments of crisis and adversity,” said Julie Foudy, who played on the 1999 squad and is providing television commentary for ESPN. “If you have a coach who believes and is calm on that bench, it makes a huge difference.”