The outcry that marked the start of the Saudi Arabia-funded LIV Golf series' first American stop quelled a bit on Friday, putting the focus on the play at Pumpkin Ridge Golf Club.

Modest crowds and mild temperatures in the mid-70s greeted the players on the upstart series - bankrolled by Saudi Arabia's sovereign wealth fund - which is trying to shake up the PGA Tour.

Dustin Johnson, the 2020 Masters winner, shared the lead with Carlos Ortiz of Mexico going into the final round of the 54-hole Portland Invitational tournament.

Johnson shot a four-under 68 to reach eight under.

"I'm really happy with the way I'm swinging it," Johnson said.

"Tomorrow, I just need to go and do the same thing, just drive in the fairway.

"I feel like I'm swinging my irons really good, so if I can get in the fairway I'm going to get a lot of good looks. And obviously I'm rolling it nice, too."

Orrtiz birdied the final hole for a 69 to pull even with Johnson.

"I felt like I played really solid," Ortiz said. "I put myself in a good position."

A lone protestor was outside the gate at the club some 20 miles west of Portland, holding a sign that simply said "Fallon Smart 2000-2016."

Smart was 15 when she was killed by a hit-and-run driver in Portland. A Saudi national attending school in Oregon was charged in her death, but removed a monitoring device before the start of his trial and vanished. US officials believe the Saudi government helped him.

The mood inside Pumpkin Ridge was light, with jugglers and other entertainment, interactive fan activities and food carts offering an array of cuisines. Organisers did not announce attendance figures but said the final round Saturday was sold out.

Branden Grace was two shots behind the leaders at six under after a 69. Justin Harding was five under after a 67, the best score of the day among the 48 players.

Australia's Matt Jones shot a second even-par 72 to be tied 17th, eight behind the leaders.

Wade Ormsby dropped to four over after posting a 76, following his 70 on Thursday.

Johnson had the biggest galleries, along with Brooks Koepka, Phil Mickelson and Bryson DeChambeau, all majors winners who have signed on to the new venture fronted by CEO Greg Norman.

The PGA Tour has responded to LIV Golf's challenge by suspending every active member who competed in the first LIV event.

Those who played in Oregon were suspended unless they resigned their tour memberships.

A big lure for the LIV golfers is money. In addition to sizable signing bonuses, the 48-man field is competing for a $20 million ($A29 million) purse, with an additional $5 million ($A7.3 million) prize fund for a team competition.

There's no cut and even the last-place finisher earns a payday of $120,000 ($A176,000).

On Thursday, a group of families who lost loved ones on September 11 protested at the tournament. Fifteen of the 19 hijackers on that day in 2001 were Saudi citizens.