On January 27th, 2010 Tommy Haas of Germany becomes a US Citizen. On March 25th of 2010 he officially starts competing on the ATP World Tour for the USA.
globalization
nacionality is not important anymore ....well only Usain Bolt seems to care about it , he has said several times that he will never race for the USA.
Never underestimate the pain of a person, because in all honesty, everyone is struggling. Some people are just better at hiding it than others.
when i remember right ,than tommy haas is an official US american citizen since begining 2010 .
so its possible.
BTW: he played german daviscup - so he can´t start for usa in daviscup )