"When I came into the league, I always thought Peter was on me all the time for whatever reason," Adu said, drawing laughter from the media. "I thought he was, but he was trying to make me better. I saw that when I went to Europe."
Nowak said the two kept in touch over the years and he has seen a growth in Adu, who is still just 22 years old.
"Sometimes it was difficult being so young, a little bit immature, to embrace the whole picture of life," Nowak said. "He showed great commitment to come back and great commitment to know what is important in life and I welcome him with open arms."
Adu has worked his way back to the U.S. National Team picture, having played in the recent Gold Cup against Mexico.
He could never match the hype that followed him after turning pro so young. Adu never became soccer's savior, but he had three solid years with Nowak and D.C. United. In 87 games with United, Adu scored 11 goals, was a two-time MLS all-star, and was a member of the 2004 MLS championship team.
Adu should begin contributing immediately.
While Nowak wouldn't say Adu would play for sure in Saturday's 8 p.m. matchup at PPL Park against Dallas, all indications are that the new acquisition will see the field.
"He is ready to go," Nowak said.
Although Adu was brought in to bring the team some offensive punch, Nowak stressed that to be a complete player, Adu has to continue working on his defensive game.
According to the source, Adu won't be a "designated player," a distinction that allows clubs to acquire up to three players whose salaries exceed their budget charges. This year a designated player's salary budget charge is $335,000 unless the player joins his club in the middle of the season, in which case it will be $167,500. The MLS salary cap is $2.6 million.
Besides being together three seasons with D.C. United, Adu was a member of the 2008 U.S. Olympic team, which Nowak coached.
Adu, who practiced with his new team Friday, played his final MLS season in 2007 for Real Salt Lake but after 11 games had his rights sold to Benfica.
He played 11 games that season for Benfica. Since then he was on loan to four different clubs, the most recent Caykur Rizespor, a First Division team in Turkey.
His new teammates are glad to have a player aboard who is expected to help the Union (8-5-9) continue their run toward a playoff berth.
"He has great vision and a great ability to wiggle out of tight space," Union defender Danny Califf said of Adu. "Freddy is coming with something to prove and I think this is a great move for us."
Adu has spent time at midfield and forward and Nowak said that will all work itself out where he plays.
"I think his natural position," Nowak said, "is starting 11."
Contact staff writer Marc Narducci at 856-779-3225, firstname.lastname@example.org, or @sjnard on Twitter.