KOHLER - Hydration and rest have become two key words for this week's U.S. Women's Open at Blackwolf Run in Kohler. With temperatures hitting triple digits, winning is no longer just about course management.

Caddies walked around with umbrellas to hold over player's heads today at the U.S. Women's Open, and wet towels were slung around the necks of others.

Volunteers in golf carts rushed back and forth to the coolers on tee boxes to replenish the quickly disappearing water.

While these women are used to playing in hot weather, the added element of being a major championship set up by the United States Golf Association might make this a true survival of the fittest.

"It is very hot out there. It's muggy," said 2010 U.S. Women's Open champion Paula Creamer. "Being hydrated and taking care of yourself is going to be a huge factor. It's just such a mental grind in itself being out there, and the fact when you add all these other elements to it and delays and whatnot. Hopefully we don't get any. This would be nice. We already had one. That's a typical U.S. Open."

Creamer, one of a handful of American favorites in the field, admitted each round is going to be physically draining.

It's why many players scaled back their practice rounds over the last two days, sometimes playing only nine holes, or as little as three or four.

"The weather is so hot, I made a plan to practice only in the morning before Noon or one o'clock - and I'm just playing nine holes," defending champion So Yeon Ryu told OnMilwaukee.com. "Practice is really important, but the most important thing is keeping in great condition physically. At the hottest moment the important thing is not too much practice, it's drinking plenty of water."

Much has been made about how difficult Blackwolf Run is, how speedy the greens are and how thick the rough is.

In the end however, the heat may be the true determining factor.