Three days after being hired as the Philadelphia Union's top assistant coach and youth development coordinator, John Hackworth arrived at the MLS expansion franchise's office in Chester yesterday and acted as if he had been there for months.

Hackworth, 39, spent the last two years as an assistant coach on the U.S men's national team and served as the technical director of U.S. Soccer's Development Academy, overseeing player development nationally since 2007.

The U.S. national team qualified for the 2010 World Cup in South Africa, so leaving that organization was not easy. But when Union head coach Peter Nowak called in August, Hackworth was immediately interested because he said he thought professional soccer could influence development of the sport at all levels in the United States.

"It was really difficult to make the decision to leave the World Cup team in a World Cup year," Hackworth said. "That was the hardest part. Timing-wise, it might not be the best time to do it, but opportunity-wise, there was never going to be a better opportunity to get into MLS with an expansion franchise that was with people I respect and trust immensely."

Nowak was an assistant on the national team with Hackworth prior to joining the Union.

Nowak said he appreciated the breadth of Hackworth's experience with youth development, from his position at the National Academy to his six-plus years at the helm of the U.S. Under-17 Residency Program in Bradenton, Fla. (Hackworth is a Florida native.)

Hackworth had a hand in the development of many of the country's young stars, such as Michael Bradley and Jozy Altidore. He will use that experience in overseeing a partnership between the Union and YSC Academy in Wayne. The arrangement will be called the YSC Union Juniors Academy and will offer training to children ages 8 to 12.

Nowak brought in a familiar face, but he said he appreciated Hackworth's willingness to disagree.

"I don't need a yes man behind me," Nowak said. "I need a guy who's going to also challenge me."

"I can disagree with Peter in a heartbeat, and he absolutely can disagree with me, but at the end of the day, it's OK," Hackworth said, stressing Nowak's authority. "We respect each other enough that it doesn't have to be that his idea or my idea is the only one."

To complete the Union coaching staff, Nowak said yesterday he may look to hire a goalkeeper assistant to oversee the entire goalkeeping program, both on the Union's first team and in its development programs.