Summary Defending champion Adam Scott, also one stroke back from Haas.
AUGUSTA (AFP) - Overnight leader Bill Haas was under attack from a pair of major winners early on in the second round of the Masters on Friday.
The 31-year-old American, who had a four-under 68 to open with, was a late starter, enjoying the luxury of being able to sit back and see who could catch him.
The 2010 British Open winner Louis Oosthuizen, who was one of three players one stroke back off the lead, dropped one at the tough par-three fourth.
Masters champion two years ago Bubba Watson, who also opened with a 69, parred the first to stay at three under.
Much of the day s focus though was on the late starters with leader Haas due out at 1715 GMT.
Defending champion Adam Scott, also one stroke back from Haas, was in the penultimate grouping at 1748 GMT with Rory McIlroy (71) the last man to tee-off in the company of Jordan Spieth (71) and Patrick Reed (73).
Three-time former champion Phil Mickelson was in danger of missing the cut for just the second time in 22 appearances at Augusta National following a first round of 76.
