When she told him it was his right foot, he replied, "That's impossible."
Roddick then turned to chair umpire Enric Molina and, pointing first to his right foot, then his left, asked, "Has THIS foot gone in front of THAT foot ever in my career?"
Molina replied: "Not in my matches."
A TV replay showed Roddick did commit a foot fault - but with his left toes.
And what really bothered Roddick, he said afterward, was that the official would not acknowledge that she was mistaken when she blamed his right foot for the ruling.
"I was just stupefied," he said.
Indeed, asked later what might have happened if the lineswoman said the call was made because his left sneaker was on the baseline, he replied: "There would have been no discussion."
Come on Roddick, stay classy! It's stuff like this that makes you lose the US open to a nobody. :(