Morikawa started the day with a six-shot lead and used to be seven transparent after overlaying the primary six holes in 3 beneath par, however would now not make some other birdie till the 18th and steadily noticed his benefit whittled away at Kapalua.
Rahm, who shot 33 beneath par in completing runner-up to Cameron Smith remaining 12 months, recovered from a bogey at the first with 8 birdies within the subsequent 13 holes after which holed from 12 ft for an eagle at the par-five fifteenth.
That took the previous global primary to inside one of the vital lead and moments later he used to be tied, Morikawa thinning a bunker shot at the 14th around the inexperienced to drop his first shot of all the week.
Morikawa, who squandered a five-shot lead and the danger to turn out to be global primary within the ultimate spherical of the Hero International Problem in December 2021, used to be understandably feeling the drive and duffed his pitch to the par-five fifteenth to card a 2nd consecutive bogey.
Spinning his way to the sixteenth off the entrance of the fairway value Morikawa a 3rd immediately bogey and Rahm’s birdie at the 18th successfully sealed victory due to a surprising last 63.
At 27 beneath par Rahm completed two pictures forward of Morikawa, whose birdie at the 18th finished a last spherical of 72.
“Should you instructed me at the start of the spherical, after that bogey, I used to be going to do what I did I don’t know if I’d have believed you,” Rahm instructed NBC.
“However at that time it’s now not like profitable is in point of fact that during thoughts, you’ve simply were given to get to paintings and get started making birdies and that’s what I did.
“On 15 is when it in point of fact changed into truth, once I had that putt to get inside one shot and figuring out how excellent I used to be enjoying, 16 and 18 are excellent birdie choices.
“That putt went in after which on 17 I couldn’t imagine it once I overlooked the fairway and we had a one-shot lead. It took slightly an effort to simply settle myself down and alter my mindset.”