Starting the day with a three-shot advantage, the big-hitting Johnson has increased his cushion to five shots.
The Irmo native won the Sentry Tournament of Champions at Kapalua Plantation Course by a dominant margin. The result will push him to third in the world rankings behind only Dustin Johnson and Jordan Spieth.
"It's no easy task to catch DJ", said Rahm, who lost to Johnson in the final of Match Play a year ago.
If you thought the fictional Happy Gilmore could smack a ball hundreds of miles, then you haven't seen real life pro-golfer Dustin Johnson let one rip from 400 yards.
Well, the PGA Tour's Twitter account on Monday posted a video of a number of near-hits that other players - from the legendary Nick Taylor to two-time major champion Zach Johnson - have enjoyed over the past several years.
Harman recovered from mistakes at 11 and 12 with three birdies to end the day in outright second, while Jon Rahm raced into contention with a stunning finish to his round as he played the final five holes in five under par to set the clubhouse target at 12 under. Having fallen out of the top ten for the first time in four years, and with Rahm Europe's top-ranked player in only his second season, it already feels like the Ulsterman is playing catch-up just one week into the new year.
The way Johnson was playing, everyone was playing for second.
As if to prove to the doubters that he had put behind him a horror Sunday at the HSBC Champions tournament in China in October, Johnson didn't just win the Tournament of Champions in Hawaii today. "I just didn't think I was going to have a tap-in". The latter overcame an ordinary start in Maui to post another top-ten finish on 12 under par. I told myself to get it to 25.
Fowler also kept a bogey off his card and reeled off three straight birdies from the 14th before parring in to return a 68, while Dufner mixed six birdies with a pair of dropped shots in his 69.
"It's a good start if I want to do it".
"But everything's going in the right direction".