'I've been waiting for that good round to come and it came today,' said Forsyth. 'Just hoping I can build on it.'
Nick Dougherty posted a 5-under 67 to finish tied for third alongside Greg Owen, Jamie Donaldson, Mikko Ilonen, Sven Struver and Robert-Jan Derksen.
Conditions were optimal for scoring early on the Majlis Course at Emirates Golf Club and Forsyth took full advantage. He played the back side first and picked up his first birdie of the day at the 13th. Forsyth then collected a pair of birdies starting at the 17th to make the turn at 3-under.
Forsyth continued his fine play on the front half. He had a pair of birdies starting at the second and grabbed a share of the lead with a five-foot birdie at the fifth to reach minus-6.
At the eighth, Forsyth dropped a 5-iron inside four feet for his seventh birdie of the day to secure the outright lead.
'The difference, really, between the rest of the season and today was I putted a lot better,' said the 27-year-old, who earned a breakthrough victory on the European Tour at last year's Malaysian Open. 'Just a little trouble on the greens and that was the difference today.
Forsyth, however, is well aware of his competition.
'Obviously if Ernie Els is sitting there it's a different ball game especially the way he has been playing,' said Forsyth. 'It's the same old story, if you want to win you have got to beat everyone.'
Els has an incredible history at this event. The South African owns the course record, which he set en route to his first career victory on the European Tour in 1994, and became the first two-time winner of this event with his title last year.
'I just like coming here,' said Els. 'I really enjoy the golf course.'
Els also started on the back nine and jumped out of the gate with three birdies over his first four holes. He added back-to-back birdies starting at the 17th to move to 5-under on his outward half.
The reigning British Open champion's pace cooled somewhat on the front side. He managed a lone birdie at the third and was eventually caught and passed by Forsyth.
'I felt good coming in today,' said Els. 'I think the greens are rolling perfect as usual. That gives you a good chance to make some birdies. All I have to do is keep it in play and play my shots and try to make some putts. I'm just trying to do what I'm doing and see where I end up Sunday. I'm feeling good about my game.'
Mark O'Meara had five birdies and one bogey for a round of 68. The American was joined by Patrik Sjoland, Brian Davis, Fredrik Andersson, Roger Wessels, Ian Poulter, Miguel Angel Jimenez, David Lynn and Kevin Na in a tie for ninth.
Thomas Bjorn, who captured this event in 2001, finished in a group at 3-under-par 69.