Five storylines from the first round of the U.S. Women’s Open

We'll be keeping an eye on the U.S. Women's Open over the next four days, so in an effort to keep you up-to-date with everything that's going on at Blackwolf Run, we're going to provide you with the top five storylines from each round. Here's a look at Day 1.

Searing heat, long rounds turn U.S. Open into a grueling test — The U.S. Women's Open is already billed as the toughest tournament on the schedule, but this year's edition had a couple add-ons that turned Thursday's opening round into a test of wills. With the heat index topping 105 degrees during the day, players were forced to not only grind out pars on a tough track, but also stay hydrated and keep their wits about them for 18 holes.

''You're not thinking 100 percent clearly all the time,'' Paula Creamer said after shooting a 1-over 73 . ''And I think that's the hardest fight and battle out there is trying to just be in the shade as much as you possibly can. I'm not the biggest sun umbrella fan, but I used it almost every hole.''

[Related: Mobile phones permitted at the U.S. Women's Open]

To make matters worse, rounds were taking in excess of 5:30 to complete during the afternoon wave, making an already grueling day feel about ten times longer. With an excessive heat warning in effect for the area through 10 p.m. CDT tonight and temperatures in the 90's expected tomorrow, the weather could be the big winner over the first two days of the major championship. The good news is thunderstorms on Saturday should drop temperatures into the high 70's.

17-year-old Lexi Thompson in contention —Here's a stat for you: At the age of 17, Lexi Thompson is playing in her sixth U.S. Women's Open. Sixth. Thompson certainly looked like a major championship veteran on Thursday, hitting 10 of 14 fairways, 13 greens en route to a 2-under 70 that has her one shot back of the lead. There's still 54 holes left in the tournament, but Thompson would make one heck of a story if she won. Not only would she become the youngest major winner in women's golf history, she'd become the youngest major winner in golf. Period. Who holds the record at the moment? Young Tom Morris, who was 10 days younger than Thompson when he won the 1868 Open Championship.

Cream rises to the top on Day 1 — Thompson was the big story of the day, but she wasn't the only marquee name on the first page of the leader board. Americans Brittany Lincicome and Crisitie Kerr are tied for the lead at 3-under, while Ai Miyazato and Suzann Pettersen are only one shot back at 2-under. We could be in for one heck of a weekend if even half of those names are in contention come Sunday afternoon.

[Related: Former World No. 1 Lorena Ochoa making a limited comeback]

Yani Tseng's struggles continue — Tseng, the top-ranked player in the Rolex Rankings, hasn't been her usual, consistent self over the last month. After she finished tied for 12th at the Shoprite LPGA Classic, she went T-59 (Wegmans LPGA Championship) and MC (Walmart NW Arkansas Championship) in her last two starts. Her struggles continued on Thursday at Blackwolf Run, where she's trying to complete the career grand slam. After going out in even par 36 with two birdies and a double, Tseng went through a four-hole stretch on the back-nine (starting on the 11th) where she had a triple, two birdies and a bogey. At 2-over she's definitely in the mix, but you can't hit it all over the map and expect to win a U.S. Women's Open.

Wrapping up the day — Stacy Lewis, who's been the hottest women's golfer on the planet over the last three-plus months (2 wins and 3 top-5 finishes in her last six starts), was 5-over on Thursday. ...Michelle Wie finished the day at 2-over (she's made made two cuts in her last eight starts). ... Cheyenne Woods, Tiger Woods' niece, kicked off her first U.S. Open with an opening round 3-over 75. "I feel pretty good about my round overall," Woods said. "It's a tough course, and I'm just happy to have survived."

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