Australian Marc Leishman matched 53-year-old American Fred Couples for the 36-hole clubhouse lead on Friday at the 77th Masters while Tiger Woods battled to move past them for the lead.
Couples fired a one-under par 71 while Leishman shot 73 to leave both men on five-under 139 while Woods was on five-under with four holes remaining.
Leishman was trying to become the first Aussie to win the Masters, but three of his compatriots were in the hunt as well, including last-group starter Jason Day at five-under with five holes to play.
Americans Jim Furyk and Brandt Snedeker and Argentina's Angel Cabrera, the 2009 Masters winner who birdied five of the last six holes, were on 140.
In the clubhouse at 141 were Aussie Adam Scott, American Jason Dufner and England's Justin Rose, Lee Westwood and David Lynn.
Still on the course at three-under were South Korean K.J. Choi, American Rickie Fowler and Aussie John Senden.