The second-ranked Scheffler played 25 holes Friday, completing a 3-under 68 in the first round and shooting a bogey-free 64 in the second to get to 10 under. He had a 2-stroke lead over Rahm and Adam Hadwin when play was suspended because of darkness.
Rahm, the former Arizona State star ranked No. 3 in the world, also returned early to finish the first round. He shot 68-66 to possibly set up a Super Bowl weekend showdown with Scheffler for the No. 1 ranking.
“That would be a lot of fun,” Scheffler said. “It looks like right now we’re one and two, but we’ll see how things shake out. A lot of guys still have a lot of golf out there to play. Should be a fun weekend.”
Hadwin had eight holes left when play was suspended. None of the afternoon starters were able to finish the round.
Last year, Scheffler beat Patrick Cantlay in a playoff for his first PGA Tour title. Scheffler added victories in the Arnold Palmer Invitational, WGC-Match Play and Masters and was the PGA Tour’s player of the year.
The Texan has hit 20 of 28 fairways and 27 of 36 greens in regulation this week.
“Around this place when you’re hitting fairways and you’re hitting it well, the golf course can kind of open up for you,” Scheffler said. “But the opposite can happen in a hurry because there’s trouble lurking on basically every hole.”
After a frost delay and gusting wind Thursday, the players faced a lighter breeze that shifted frequently.
“The wind was really moving around,” Scheffler said. “It could be difficult to judge at times. But it was nice and warm, so it was good.”
Rahm opened the year with consecutive victories in the Sentry Tournament of Champions and The American Express. He had his best finish at TPC Scottsdale in 2015, when he tied for fifth as an amateur.
Rahm played a four-hole stretch in 4 under on his first nine in the second round. He birdied the par-5 13th, holed out of a greenside bunker for eagle on the par-5 15th and made a 7-footer for birdie on the par-3 16th.
“I hit a lot of great tee shots today,” Rahm said. “A lot of good iron shots that … didn’t end up in great spots.”
His mother and 87-year-old grandmother, visiting from Spain, watched him on No. 16.
“Unexpected. Very unexpected,” Rahm said. “I’m glad I didn’t know until I hit the shot, honestly, because otherwise I think I would have tried too hard for my grandma to hit a good shot.”
While Scheffler and Rahm topped the leaderboard, top-ranked Rory McIlroy had to rally after an opening 73 in the toughest conditions Thursday. He had four birdies in a five-hole stretch and was 3 under overall when play was suspended.
McIlroy is trying to make it three wins in a row on the PGA Tour after taking the Tour Championship in August and The CJ Cup in October. He also won two weeks ago in Dubai on the European Tour in his first start of the year.
Jason Day was 6 under, finishing off a 65 to take the first-round lead and adding a 71.
“I’m glad I’m in the house,” Day said. “I’m just going to go rest up.”