Oosthuizen used the hole-in-one to move to even par, which is where he ended his first round.
MORE: British Open winners | 2016 Open images | Opening round at Troon
Though even par is never a poor way to start a major championship, scoring was low Thursday with calm winds and relatively soft conditions at Royal Troon. Oosthuizen will have to make birdies as the week goes on if he wants to contend again.
Oosthuizen, the 2010 Open winner, lost in a playoff to Zach Johnson last year.
