The Spaniard has a remarkable CV, with a Major Championship, four Rolex Series victories and a Harry Vardon Trophy on his mantlepiece at the age of just 27, but he has yet to win a WGC crown.
He lost in the final to Dustin Johnson at Austin Country Club on his debut five years ago and got his 2022 campaign up and running with a 4 and 2 win over Colombia's Sebastian Munoz in Group One.
Munoz birdied the third to go 1 Up but that would be the only time he led as Rahm claimed the next with a par.
He then birdied the sixth to sit 1 Up at the turn and back-to-back gains on the 12th and 13th put him in command before he closed out a bogey-free victory with a fourth birdie of the day on the 16th.
"It's a good one," said Rahm. "I played a solid round of golf. If I wanted to be picky it was just a couple of short putts I would like to have made.
"But I was able to have a couple of fortunate moments. A chip in on two, the long putt on 13, a good break off the tee on 12. So everything evened out.
I'm here to compete and win and prove myself - Jon Rahm
"Sebastian didn't have his best day. Luckily, a couple of good par putts on ten, 11 and that got my confidence up.
"I'm here to compete and win and prove myself."
Cameron Young was the other winner in Group One, beating Patrick Reed 1 Up.
One of the most anticipated matches of the day was that between huge-hitting Bryson DeChambeau and 49-year-old debutant Richard Bland.
Englishman Bland was one of the great stories of the 2021 season, winning his first DP World Tour event at the 478th time of asking and then becoming the oldest ever 36-hole leader at the U.S. Open - where DeChambeau was defending champion.
He has brought that form into 2022, losing a play-off to Viktor Hovland at the Slync.io Dubai Desert Classic to sit third in the DP World Tour Rankings in Partnership with Rolex and he claimed a half with DeChambeau after a scrappy encounter in Group Nine.
A birdie on the fourth edged DeChambeau in front but Bland birdied the next before DeChambeau once again edged ahead with a gain on the sixth.
A par was enough to hand Bland the tenth and the duo could not be separated on the way home, each making a birdie and a bogey to go with six pars.
“Bryson was probably a bit rusty and it was never going to be pretty golf,” Bland said. “So I think a half was probably right.”
In the other match in Group Nine, a back-nine fightback from Lee Westwood came too late as he lost 3 & 2 to Talor Gooch.
In Group Eight, Johnson was a 3 & 2 winner over Mackenzie Hughes, while Max Homa beat Matthew Wolff 3 & 1.