Such is his determination to improve and succeed on the PGA Tour.

Sweden's Noren, a nine-time winner on the European Tour, came within a whisker of bagging his first victory in the US in January only to be defeated by Jason Day in a sudden-death playoff at Torrey Pines.

Even after a four-under-par 66 on day one at the Honda Classic saw him tie former US Open winner Webb Simpson for the lead, Noren said his job wasn't done.

"I'm going to work; I'm going to go play some holes on another course and try to figure out how to play all these different iron shots," World No.16 Noren said after his round.

"This golf course is an iron paradise if you've got that going."

Noren hits his tee shot on the 14th hole during the first round of the Honda Classic at PGA National Resort and Spa. PHOTO: Mike Ehrmann/Getty Images.

After a windy round at Florida's notoriously difficult PGA National course, World No.4 Justin Thomas, Morgan Hoffmann, Daniel Berger, Mackenzie Hughes and former Open Championship winner Louis Oosthuizen (67) share third at three under.

Known as one of the hardest workers in golf, a photo of Noren's heavily blistered hands brought on by an extensive driving range session went viral on social media in December.

Noren, who rocketed into the top 10 in 2016 from outside the world's top 100 courtesy of four wins in Europe, has targeted US golf as the final frontier he wants to conquer.

"I came over here to try to play some more American-style courses; firm greens, more rough, and to improve my driving and improve my long game," 35-year-old Noren said.

"(This year has) been great. The second place at Torrey Pines was a highlight, even though I wanted to win it."

- Evin Priest, Australian Associated Press