Yoon's second-round 69 vaulted the South Korean to 12 under for the $13 million ($A18.2 million) championship, as Davidson lost touch with a two-over 74 on Friday (Saturday AEST).
"This is actually my first time being in the lead going into the weekend. It's actually really nice experience for me," Yoon said.
"I'm so excited to play last two more days. Sometimes players have to focus on their play, but when they really want to win then they get nervous.
"That's happened to me as well. So two more days I will try to focus on my stuff and just have fun with my caddie, Kevin, out there. That's my goal."
Davidson rebounded from a first-hole double bogey with two-mid round birdies to return to seven under, only to drop another two shots late on the par-4 16th.
The setback leaves the 27-year-old seven strokes off the pace entering the weekend of women's golf's third major of 2026.
"I felt a little bit under pressure today actually. I've never been in contention in a major after the first round, so it was a little bit of a different experience for me," Davidson said.
"And I hit two bad shots that cost me two doubles but really grinded in the middle and made a couple of birdies.
"Still seems like I'm in contention, so it was good to get that pressure out of the way today, and then I can hopefully have a couple good rounds on the weekend."
Haeran Ryu fired a brilliant bogey-free 64 to emerge as one of Yoon's closest challengers at seven under, alongside fellow South Korean A Lim Kim (70) and Canada's dual major winner Brooke M Henderson (68).
Chasing a third straight major for the year, world No.1 Nelly Korda is lurking ominously at six under after making her move with a second-round 68.
Korda was seven back after the first round of this month's US Open before storming to a fourth career major at Riviera and knows the tournament is only just starting.
"It is hard to have a big lead going into the weekend," Korda said.
"I was there at Chevron and you do feel a little bit more pressure, like everyone is hunting you down.
"I'm just going to focus on, as boring as it is, one shot at a time and see where that takes me."
The American is sharing sixth spot with Korean Dongeun Lee, who opened with a pair of matching 69s.
Davidson is tied for eighth with Thailand's Patty Tavatanakit and China's Weiwei Zhang, who both carded second-round 68s.
Two other Australians made the cut with Robyn Choi (71) and Grace Kim (71) both in red numbers at one under.
Superstar Minjee Lee missed the cut as the defending champion for the first time in her glittering career.
The triple major champion missed a weekend tee time by one shot after slipping to two over with a second-round 75.
Hannah Green, who won her first and still only major at Hazeltine National Golf Club seven years ago, also finished at two over after a 74 on Friday.
Gabriela Ruffels (73-73) was also two over, with Cassie Porter (74-77) seven over.
