Oosthuizen, nicknamed after the animated character "Shrek" because of his gap teeth, returned to the Kuala Lumpur Golf and Country Club in the morning to complete his six holes of the second round with two more birdies for a four-under-par 68.
Countrymen Jbe Kruger, leader of the Asian Tour's Order of Merit, and Hennie Otto trail Oosthuizen, the 2010 British Open champion, by one with Scotland's Stephen Gallagher in the US$2.5 million tournament sanctioned by the Asian Tour and European Tour.
The third round will start at 11.40am with the leading group going off at 1.30pm.
Oosthuizen travelled for nearly 30 hours from Augusta to Kuala Lumpur where he spent "every second" reflecting on his play-off defeat to American left-hander Bubba Watson in the year's opening Major.
The 29-year-old South African, who entered Masters folklore with an albatross on the second hole during the final round, has shown no ill effects of jetlag to shoot up the leaderboard in the Maybank Malaysian Open.
Two birdies on 14 and 15 put him in the driver's seat but Oosthuizen knows there is plenty of golf yet with 16 players being five shots off the lead with 36 holes remaining.
"I felt comfortable as I had a good night's rest and I felt good this morning at the range and hit a few good shots," said Oosthuizen, who leads on 10-under-par 134.
"I like the golf course. I didn't play very well last year but it's a good track. Greens are a bit different from Augusta, quite grainy and not as fast. But I think there are a lot of birdie opportunities out there if you hit the greens. You adapt quickly.
"I think you get used to the travelling and stuff. You know beforehand that it's going to be tough and your mindset is as such that you know it's going to be tough. But it's been okay. I can do with minimum sleep. I'm fine with it. You just get tired when it gets to six or seven (in the evening) and last night I was out cold at 7.30 but up early in the morning. It's one of those things. It's a tough week but you prepare yourself mentally for it."
Oosthuizen said he has not thought much about his near miss at the Masters Tournament as he chases a fifth European Tour victory and first in Asia.
"It's always going to be at the back of your mind. Once you're on the golf course, you don't think about anything. You just think about the game on the day. It's difficult (though) sitting wherever in the clubhouse and they are showing the highlights of last week. It's a week where you want to forget. I've got three weeks after this and it'll help a lot just focusing on the year ahead," he said.
Two-time Asian Tour number one Jeev Milkha Singh joined countryman Jyoti Randhawa on 138, four behind the leader, after completing his second round in 73, shooting one birdie in his last six holes this morning.
"I struggled with my driving yesterday. I was two-over for the 12 holes that I played. I'm still in there, I'm four shots behind and I'm looking forward to the next two days," said Singh.
"The rain suspension helped. I went back to give it a good thought. I told myself to think positively about the driver because my driver cracked during the pro-am day so I'm using a new driver. I tried it and it was really good on Thursday and it wasn't up to the mark on Friday. I'm getting used to it and will make the most out of it in the next two days."