I guess guys like Rory McIlroy, Charl Schwartzel, Louis Oosthuizen don't count as dark horses, but maybe :
Kyung-tae Kim
John Senden
Bubba Dickerson
Robert Rock
Chez Reavie
Johan Edfors
to mention some of the names on top of the leaderboard after the first round.
My favorite dark horse is
Robert Rock
http://www.golfchannel.com/news/asso...n-spot/?hj=xfs