The South African has struggled with a back problem in recent weeks, but says he is now over the injury and in good shape.
Oosthuizen, who was runner-up at Augusta in 2012 after losing a play-off to Bubba Watson, is keen to go one step further and claim the famous green jacket when the tournament concludes on Sunday.
"Coming so close in 2012 hurt a little bit but I'm confident one of these years I'll pull it off," he said.
"I feel confident. I need to put a few rounds together, the start is very important. I've got to play well on Thursday to give myself a bit of momentum.
"I've had lots of troubles since October so I did a few things to try and sort it out so hopefully it stays away now."
Oosthuizen, who won The British Open in 2010, singled out the 505-yard par-four 11th as the trickiest of many difficult holes around the fabled course.
"The most difficult hole is probably the beginning of Amen Corner, the 11th," he said.
"Your round can go very bad there or you can put yourself in a really good position with two par fives to come.
"There aren't many easy holes at Augusta but 11 probably stands out."