What unique thing has Federer achieved in his last 21 first round Grand Slam matches?

And who was the last player to interrupt this streak and when did it happen? This trivia question was just posed by Darren Cahill on ESPN so if you're up early to watch the Rafa blowout, you should know the answer. First person with the correct answers gets the 10 points. Rafa looks superb btw though I'd like to see him against some stiffer competition.