Bryson DeChambeau is looking to unleash a "scary combo" if he can improve his accuracy at the Omega Dubai Desert Classic.
DeChambeau, who claimed a seven-shot win in last year's event, opened his title defence with a two-under 70 to stay within three strokes of early leader Thomas Pieters.
The American mixed four birdies with two bogeys in tough scoring conditions at Emirates Golf Club, where narrow fairways and thick rough saw only 29 of the 132-man field finish under par.
DeChambeau added muscle mass during the off-season to increase how far he hits the ball, with the 26-year-old now aiming to keep the ball in play more to take advantage of his added length.
"It's playing at least four shots harder a day (than last year) if it was to stay like this, no doubt," DeChambeau told Sky Sports. "The fairways are tightened up.
"It's a very, very good test of golf and you have to make sure your wedge game is on and your iron play out of the rough is on because you're going to be in there.
"I'm still working on the driver, it's a work in progress, but it will be a work in progress until I can get the right stuff in my hands.
"The shot I hit on five, it was off line but it was still so far up there that I had a wedge in my hand. At six I hit it 350 (yards) just into the first cut. I hit it really far, I can do that and now it's just about controlling it and if I can control it it's going to be a scary combo."
David Lipsky sits in second after a four-under 68, while Eddie Pepperell took inspiration from Lee Westwood's win in Abu Dhabi last week to change his putting style and post an opening-round 69.
"I'm really happy with that," Pepperell said. "It was clear early on it was going to be very, very challenging. I played a good round of golf today and proud of that, if you know my record on Thursdays.
"The claw grip was inspired a little by Lee (Westwood). I must say, I've been struggling with the greens. I've never been a good putter on Tour, but for me, it's about not being a terrible putter.
"I was watching the golf last Sunday and I couldn't believe how comfortable Lee looked on the short putts, especially. I thought, I might as well give this a try. I was very good today inside six, eight feet. So I'm optimistic. Best I've putted for a while."
Watch the Omega Dubai Desert Classic throughout the week live on Sky Sports. Live coverage continues on Friday from 7.30am on Sky Sports Golf.