The signs are unmistakable. Grandstand seating, white corporate tents and sponsor insignia dot the fairways and greens around TPC Twin Cities in Blaine, with more popping up by the day. The PGA Tour's 3M Open is a month away and the finishing touches are being put on the reworked course.

Course co-designer Tom Lehman gave input for the changes and, on Monday, got his first up-close look at the narrowed fairways, new tee boxes and higher rough — which, with some moisture and heat, will thicken in the next four weeks.

Lehman spent the morning exploring the property on a golf cart, and probably taking some keen mental notes. The 60-year-old Minnesota native confirmed he has accepted an exemption into the tournament, his first non-major start on the PGA Tour since missing the 54-hole cut at the 2015 Pebble Beach Pro-Am.

"You don't get this opportunity every day," said Lehman, who last summer commented he would not play in the event. "Am I going to want to play out here when I'm 65? Probably not. But I am still hitting it far enough where I think I can manage even the longer holes that we have. So why not?"

When he tees off in the 3M Open, he'll find a course that has been reduced to a par 71 (No. 3 will play as a 500-yard par 4) and lengthened to just under 7,500 yards.

There might not be many — any? — holes that will tame young long hitters committed to the field such as Brooks Koepka, but Lehman said that's fine. Some of the changes are "sneaky," he said, and that will be enough to make players think.

"Those can be some of the best changes you can make," he said. "The average person might not notice it, but I certainly will."

More exemptions

Wayzata's Tim Herron also accepted a special exemption from the 3M Open. Herron, 49, has played in only six PGA Tour events this season and for a time figured the next appearance in his home state would be after age 50 on the Champions Tour. Then the 3M Open showed up on the schedule and came calling.

"I'm glad to be a part of it," Herron said.

The four-time PGA Tour winner played TPC Twin Cities on Monday and expects a pin-seeking affair when the full field arrives.

"Everyone is focused on making courses the hardest but … you have to have some variety," he said. "For the fans, with guys making birdies, it's a lot more fun. It's more of a fest than the Fourth of July."

Tournament Executive Director Hollis Cavner also said the 3M Open has given sponsor's exemptions to a pair of amateur golfers from Oklahoma State, Viktor Hovland and Matthew Wolff. Hovland, 21, shot 3 under at this year's Masters and was low amateur. Wolff, 20, won last week's NCAA individual championship.

"We want the young guys [here] to establish a loyalty factor," Cavner said. "And these are two extraordinary young players."

Planning a side trip

World No. 8 Bryson DeChambeau was the first big-name player to commit to the field. Something of a mad scientist on the golf course, DeChambeau said 3M's innovative product background was one of the factors in luring him to the event and he will visit the company's headquarters during tournament week.

"That's a big deal for me," he said. "I love hearing about and understanding the growing of human potential. I'm excited to see what they're doing for the world."

As for the golf?

"Great fans up there," he said, noting his attendance at the 2016 Ryder Cup at Hazeltine. "I'm excited to see how everyone reacts to four days of golf."

Tiger update

Cavner, never one to shy away from a microphone, was noticeably tight-lipped when asked for an update on the tournament's pursuit of Tiger Woods.

"We'd like to see Tiger here, and we'll be very happy if and when he decides to commit," Cavner said. "That's the answer that I'm allowed to give."