Shooting his second round of 6-under 66, McKenzie leads the tournament by two shots heading into the third round.
Meanwhile in the Victorian PGA Amateur Challenge, the AFL Footy Show's Sam Newman leads with one round to play. He combined with big hitting Professional Steve Jones to shoot 20-under the card in a 4BBB format.
Newman and Jones will tee off at Huntingdale Golf Club at 7.36am playing alongside Ricky Ponting and Daniel Popovic.
Super consistent over the past two days, McKenzie is enjoying his time competing on the Huntingdale layout which suits his game style so well. Playing conservative and accurate golf he has only one bogey on his scorecard in 36 holes.
It's an important week for McKenzie who is chasing his first victory since 2014 as well as a place in the lucrative Perth International at the end of the month.
Playing in the morning field, overnight leader Brad Shilton has had a roller coaster round on course. Counteracting four soft bogeys with six birdies he posted a 2-under 70 to be outright second on 10-under the card, trailing McKenzie by two shots.
Defending champion Aaron Townsend jetted into Melbourne from Asia on Monday but his lack of practice round hasn't affected his performance.
He fired 5-under 67 in the second round to be tied third with Ash Hall who like McKenzie is needing a win to gain a start in the Perth International.
Aron Price and Anthony Houston, who won Qualifying School, are tied fifth on 7-under the card.
A shot further back and rounding out the top-10 are Peter O'Malley, Mark Brown, Michael Sim and Todd Sinnott.
The second round cut at the Mercedes-Benz Truck and Bus Victorian PGA Championship was made at even par with 57 players making the final two rounds.
The third round of the Mercedes-Benz Truck and Bus Victorian PGA Championship tees off at 7.25am with the lead group of McKenzie and Shilton on course at 12pm.
David McKenzie, 66, 66, 12-under, 1st
"I was pretty happy with it. I got off to a very good start and then had a very good finish."
"I struggled on 16, 17, 18 and 1. I missed a four footer for birdie, I missed a six footer for birdie and that sort of set my confidence back, then I three putted for bogey on the 1st. But then I finished with a couple of good ones by knocking it on the two par-5's."
"Huntingdale works for me because there are no bunkers to drive over. If you are smart about it you can control where it goes then it's a little bit easier for someone who plays the way that I do. You can get in trouble quick if you get greedy."
"A win gets me into the Perth International which is probably the biggest thing. I didn't realise I wasn't in until late last week so that added a little more momentum or reason to play better this week."
Brad Shilton, 64, 70, 10-under, 2nd
"I think at the start of the day I would have been happy enough with 2-under. I played pretty well for most of it but I made a couple of soft bogeys on my first nine, which was the back-9, but a couple of birdies to finish so happy enough."
"I didn't feel like I played terribly at all, just a couple of soft bogeys early on. I never really felt like I was chasing or having to make up for any bad play. It was nice to make a few birdies once you have dropped a couple."
Aaron Townsend, 68, 67, 9-under, T3
"It's exactly how I would have liked to start. I played nice today in the wind, it was quite tricky. I played better today than yesterday. I putted and scrambled really well yesterday and I was happy with how I hit the ball today. Hopefully I can put it all together as the next two days come. "
"The greens are starting to firm up quite a lot so I expect the course to get quite fiery over the next two days."
"I have played here so much and obviously the good memories from winning and not having a practice round wasn't a big deal. As well as I know the golf course, I probably don't even need a yardage book in a way."
Ash Hall, 66, 69, 9-under, T3
"I managed it really well today and stuck to my game plan. I'm striking it really well so I was never in trouble, no bogeys is a good thing."
"I'm here to win; I need to win to get into the Perth International. It would be good to get my hands on the trophy; it's even been a while since I have won so that is what I want."
"I like to think I have an advantage around this course in particular. But Brad Shilton and David (McKenzie) are the kind of players that will play well around here, the Peter Senior types."
Anthony Houston, 67, 70, 7-under, T5
"I played really well yesterday, today was a bit of a battle but just got the job done in the end. I tried to stay as calm as I could and hole a few putts."
"Yesterday afternoon when I played it was really windy, at least a one or two club wind. Today it was really still. Sometimes the wind helps you focus on the shot that you want to hit, where as today you can go for a bit much around here and it's pretty tight so you can make some soft bogeys."
"It was really good to win (Q-School) because it gets you into everything and second may not."
"Missing the cut last week was probably a good thing. It brings you down to earth and I did some good work over the weekend and it seems to be working so far this week."
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