Fate intervened. Reading's then manager, Alan Pardew, signed the 6ft 3in goalkeeper, initially as cover. Hahnemann underwent a transformation from spare part to vital component of the Royals' Premiership promotion machine. Just under four years on, and he is preparing for life among the élite of England - once he has enjoyed the experience of facing the world's best in Germany.
Life could hardly be more propitious for the custodian who has thrived in his adopted land, yet harbours no doubts about his true allegiance. Though he is the son of two German parents, Hahnemann has a tattoo of the Stars and Stripes on his arm, is known as "Buddy" to his Reading team-mates, and at home in the United States has a collection of shotguns. He is American as peanut butter and pecan pie.
You swiftly gain the impression that the goalkeeper blessed with agility and strength would do just about anything short of using that collection of weaponry to ensure that he contributes to his nation's effort in Germany. The contest is between him, Kasey Keller and Tim Howard for the No 1 position in Bruce Arena's starting XI. But just being there is sufficient.
The US squad, who also include the Reading midfielder Bobby Convey, have played three friendlies in the past two weeks. They were defeated 1-0 by Morocco, but overcame Vene-zuela 2-0 and Latvia 2-0. Hahnemann was an unused substitute in all three. "Bruce'll probably start with Kasey in the tournament," says Hahnemann of the 36-year-old former Millwall, Spurs, Leicester and Southampton goalkeeper, currently with Borussia Mönchengladbach.
"This is his fourth World Cup and he's got 90-something caps. He's one of my really good friends and we get along really well. I would never wish anything bad on him. But it's the same old story. I want to play."
However, Hahnemann adds: "I was just desperate to be in the squad. I told Bruce that I would carry bags if I needed to. I will try to do things exactly the same as I do playing as first choice for Reading, so that if do get a chance to play, I'm 100 per cent and ready to go. Otherwise you could end up letting yourself down, and your team and your country."
The US, who are fifth in the Fifa rankings, reached the quarter-finals in Japan and South Korea before being eliminated by the eventual losing finalists, Germany, 1-0. This time, their initial task is more daunting, given the opposition of Italy, Ghana and the Czech Republic in Group E.
Hahnemann, approaching 34, concedes: "It's a hard group. Everyone's calling it a 'Group of Death'. But we have a really good team, and team spirit. There's seven guys in our team from England but otherwise we play in all different countries, so you don't get to see the other guys very often. But when we come together, we play together. The team spirit we have is unbelievable - and that's something we've replicated at Reading this year."
He adds: "There's no reason why we can't progress from the group. Stranger things have happened, as we saw at the last World Cup. It's only three games, and you don't have to win them all and you don't have to win your group. Once you're in the knockout stages, you just have to be hot at the right time."
Ask a man who played football, baseball, American football and basketball as a boy to what he attributes his own remarkable advancement, and he talks about his routine: four cans of Red Bull and the pounding rhythms of Slipknot. "Really hard, heavy metal," he adds helpfully of his musical preference, though it is a far-from-head-banging, meticulous 45-minute pre-match warm-up routine which aids his concentration that is probably the main factor.
It was his father's ultimatum at 16, "choose a sport or get a job", which ensured that Hahnemann focused on a specific game. "When I was 16, I had a car and my dad paid for the gas, insurance, and for all my spending money," Hahnemann recalls. "But then one day he said I should choose one sport and take that one seriously. He said: 'If you stop playing sports, you're going to have to get a job, to pay for your car'.
"I went, 'Oh, in that case, I think I really like soccer'. In fact, soccer picked me. I was a lot better at it than anything else. I kept improving, got a university scholarship to play, graduated with a teaching degree, won a national championship with the team, and then signed for the local pro team. It's pretty amazing how things have worked out."
Not least for him and his Reading team-mates in the Championship during recent months. "It has been so ridiculous," says Hahnemann, who lives with Amanda and their two football-crazy young sons, Hunter and Austin, near the Thamesside town of Pangbourne. "To get promoted, no matter how you do it, is the ultimate goal, but the way in which we kept going in every game and never let up, finishing with 106 points, that's the amazing thing."
Perhaps it offers something for Bruce Arena's Team US to derive inspiration from.
Giant-killings: Six results that shook the world
1950 USA 1 ENGLAND 0
England's first World Cup ended in disaster in the heat of Brazil's Belo Horizonte as they rested Stanley Matthews and lost to a team containing only one professional. Joe Gaetjens, a Haitian, scored the only goal.
1954 W GERMANY 3 HUNGARY 2
West Germany only qualified for the knockout stages via a play-off against Turkey having been hammered 8-3 by Hungary in the group phase, and were 2-0 down in the final at Berne after eight minutes. But it was 2-2 after 19, and an 85-minute winner saw off the Hungarians, Puskas and all.
1966 N KOREA 1 ITALY 0
Ayresome Park saw an awesome result as Pak Doo-Ik's 42-minute goal meant his side qualified from Group Four at Italy's expense. The Italians, reduced to 10 men after 30 minutes, returned home to a hail of tomatoes.
1982 ALGERIA 2 W GERMANY 1
Algeria maintained their 100 per cent record against the Germans (they had beaten them 2-0 in 1964) in Gijon, Spain, with Lakhder Belloumi's 69-minute winner. But it was the Germans who qualified from the group, to reach the final.
1990 CAMEROON 1 ARGENTINA 0
The champions lost in the group phase in Milan, going down to a 67-minute strike from Francois Omam Biyick after Cameroon had been reduced to nine men. But Argentina scraped through as third-best losers to reach the final.
2002 SENEGAL 1 FRANCE 0
Papa Bouba Diop scored the only goal after 30 minutes to humiliate the World Cup, European Championship and Confederations Cup holders in their opening game. France crashed out while Senegal, in their first finals, reached the quarter-finals.
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