It seems a theme has developed at USGA Open Championships in 2017: rainfall, followed by humidity and light winds, has yielded excellent scoring conditions. Red numbers were a-plenty at both Erin Hills (U.S. Open) and Salem Country Club (U.S. Senior Open), and the competitors at the 72nd U.S. Women’s Open joined the party on Thursday. Before darkness halted play at 8:33 p.m. EDT, 46 players were under par at Trump National Golf Club – on pace to surpass the first-round record of 44 set at Old Waverley Golf Club in 1999, with 12 of the 46 still to complete their rounds early on Friday.

Shanshan Feng leads the way after an opening 6-under 66, but several major champions are lurking, including Lydia Ko and So Yeon Ryu, who shot 4-under 68s, and Cristie Kerr, playing in her 22nd Women’s Open, who stands at 3 under.

The field will be cut to the lowest 60 scorers and ties after the second round – which will hopefully come on Friday, if Mother Nature allows. As those close to the lead jockey for position, we’ll see if Jessica Korda (3-over 75), Inbee Park (5-over 77) and Ariya Jutanugarn (7-over 79) can rally to stay for the weekend. Here’s what else to watch for today:

Winning Time?: You’ve heard the phrase “horses for courses” before. The Women’s Open isn’t played at the same venue each year, but Amy Yang always seems to find herself near the top of the leader board. A day after two-time champion Juli Inkster suggested Yang had the perfect ball flight to contend at Trump National, the 27-year-old from the Republic of Korea fired a 5-under 67 and is in second place. “The U.S. Open is one of my favorite tournaments and I enjoy being here,” said Yang, a two-time runner-up. “I like more difficult courses, they make you more focused.” Yang has been in the top three through 36 holes in each of her last three Women’s Opens. We’ll see if she can make that four in a row on Friday.

Kirk Staying Hot: Last week, Australian Katherine Kirk won the Thornberry Creek LPGA Classic, her first victory since 2010, to earn an exemption into the Women’s Open field. Kirk had planned to go back home to Wichita, Kan., for a week off, but the 35-year-old welcomed the extra week of work. She opened her 13th Women’s Open with a 2-under 70 and will attempt to become the second player since 1981 to win the championship following a victory. In 2013, Inbee Park won the two events immediately preceding her victory at Sebonack Golf Club. Kirk will look to post her sixth consecutive sub-par round on Friday.

What the Heck?: While other 15-year-olds are enjoying their summer vacations, Rachel Heck is having a great time on the first page of the leader board at the Women’s Open. The youngest player in the field didn’t have a bogey on her scorecard and was 3 under through 13 holes when play was suspended. Though Heck will only be a sophomore at St. Agnes Academy in Memphis, Tenn., she has already verbally committed to Stanford University. On Friday, she will attempt to become the youngest player to make the cut in the Women’s Open since Nelly Korda did so as a 14-year-old in 2013.

Green Monsters: While the fairways at Trump National are generous relative to Women’s Open standards, approach shots require strategy and precision to get close to the hole on the sprawling greens. The average green size on the course is 7,000 square feet, including the 14,000-square-foot putting surface on the par-4 sixth hole. Comparatively, the greens at Pebble Beach (Calif.) Golf Links, the smallest in championship golf, are approximately 3,500 square feet each. “You almost have to look at them as separate greens and get your ball in the different areas because they're just massive,” said Kerr, the 2007 champion. “The sixth is probably the biggest green I've ever seen. It can be a little intimidating because you can hit the green, but end up a mile away from the hole.”

Records Falling: Calm winds and receptive greens contributed to ideal scoring conditions on Thursday. The record of 135 sub-par rounds for an entire championship (set at Old Waverly in 1999) is in jeopardy and several players have their sights set on Helen Alfredsson’s 36-hole scoring record of 132 set in 1994. Because Trump National is a par 72, this championship is unlikely to break the record for lowest cut, but it could be the lowest cut in relation to par since 1999. Rain fell overnight, and more showers moved through during the early-morning restart on Friday, so those who played on Thursday afternoon will get a crack at a soft and susceptible Trump National on Friday morning. Let’s see how low they can go.

Michael Trostel is the senior content producer for the USGA. Email him at mtrostel@usga.org