King Abdullah Economic City - Thomas Pieters fired a bogey-free seven-under-par 63 to leave the big names in his wake in the opening round of the inaugural edition of the controversial Saudi International on Thursday.
The world's top three, Justin Rose, Brooks Koepka and Dustin Johnson, are all competing this week despite a wave of criticism over Saudi Arabia's human rights record.
Pieters made the most of kinder morning conditions to roll in seven birdies and take a two-shot advantage.
Earlier on Thursday, European Tour chief executive Keith Pelley defended the decision to hold the Tour's first-ever event in Saudi Arabia.
"We obviously evaluate first and foremost the safety of our players and our staff," he told AFP at the Sport Business Summit in Abu Dhabi. "We're excited that the Saudi International is on our schedule."
England's Paul Casey opted out, while world number one Rose protested "I'm not a politician, I'm a pro golfer" as he explained his decision to play.
Pieters, a three-time champion on the European Tour but without a title since his triumph in Denmark in 2016 that secured him a Ryder Cup spot that year, started from the 10th tee and made three birdies before making the turn and adding four more on his way back.
The Belgian leads a group of six players tied for second after rounds of 65, including England's Ross Fisher and in-form South African Justin Harding.
Rose struggled after the long trip from Torrey Pines where he won the Farmers Insurance Open last week and opened with an even-par 70.
The second-ranked Koepka was marginally better with a 69, while Johnson and world number five Bryson DeChambeau shot two-under-par 68s playing in the afternoon session.
Pieters, who won the World Cup of Golf for Belgium with Thomas Detry in November last year, credited his round to some fantastic approach shots.
"I hit my wedges and short irons really close to the hole. I think I had maybe ten good chances for birdie and made seven of them. It was a very good day on the greens, with a couple of long putts, as well," said Pieters, who has slipped to 76th in the world rankings.
Rose, on the other hand, blamed his putting for a round that saw him make just three birdies.
"We had it calm this morning and knew tomorrow afternoon the wind is going to pick up, so you had to take advantage of the golf course this morning," said the 38-year-old.
"I had the opportunity to hit a lot of shots close to the hole but couldn't make the putts."
DeChambeau, who is also coming off a win last week at the Dubai Desert Classic, struggled for the better part of his round before making three birdies in his last five holes to get under par.
"I just kept fighting, wasn't hitting my irons exactly the way I wanted to, wedging it awful, but it was just exposing something that I need to work on, but really proud that I fought back and was able to finish two-under today," said the American who has won four times in his last nine starts.
Sergio Garcia, the 2017 Masters champion, started with a one-under-par 69.
Leading first-round scores from the European Tour's Saudi International on Thursday at the par-70 Royal Greens Golf Club (GBR & IRL unless stated/am denotes amateur):
63 - Thomas Pieters (BEL)
65 - Alfie Plant, Ross Fisher, Justin Harding (RSA), Jake McLeod (AUS), Zander Lombard (RSA), Renato Paratore (ITA)
66 - Shaun Norris (RSA), Victor Perez (FRA), Joost Luiten (NED), Jorge Campillo (ESP), Justin Walters (RSA), Matteo Manassero (ITA), Chris Paisley, Richard Sterne (RSA)
67 - Joachim B Hansen (DEN), Marcus Kinhult (SWE), Bradley Dredge, Wu Ashun (CHN), Patrick Reed (USA), Lorenzo Gagli (ITA), Ryan Fox (NZL), Scott Jamieson, Christiaan Bezuidenhout (RSA), Rayhan Thomas (Am-IND), Fabrizio Zanotti (PAR), Romain Langasque (FRA), Li Haotong (CHN), Matthew Southgate, Pablo Larrazabal (ESP)
68 - Haydn Porteous (RSA), Sam Horsfield (ENG), Gaganjeet Bhullar (IND), Niklas Lemke (SWE), Robert Karlsson (SWE), Henrik Stenson (SWE), Thomas Detry (BEL), Paul Dunne, Richie Ramsay, Dustin Johnson (USA), Bryson DeChambeau (USA), Ian Poulter, Mikko Korhonen (FIN), Gavin Green (MAL), Gonzalo Fernandez-Castano (ESP)
69 - Brooks Koepka (USA), Lee Westwood, Sergio Garcia (ESP)
70 - Ernie Els (RSA), Justin Rose