Bubba Watson hit a 10-under-par 62 to put him in the lead after round two of the WGC-Cadillac in Miami Florida.
The impressive round is the second-lowest ever score on Doral's Blue Monster course.
The American, who started the day in 13th, is one shot ahead of Justin Rose after the Englishman carded a round of 64 to end the day on 11-under.
Australian Adam Scott's 68 left him on 10-under, while Sweden's Peter Hanson is one shot further back.
Newly-crowned world number one Rory McIlroy struggled again as a 69 saw him end the day on two-under.
